Re: [BUG] add_dns_server() adds bogus IPv4 nameserver address

[David Fifield <david () bamsoftware com>]

On Wed, Jan 13, 2010 at 11:19:17PM +0000, jah wrote:
> It wasn't after all, getaddrinfo() that was the problem.  After a lot of
> head scratching, I had a look at my nmap-exp branch where I began work
> (a long time ago) on ipv6 support for mass_dns.  I found that the
> current code in get_dns_servers() uses inet_ntop() to convert a
> sockaddr_storage to a string, whereas in my exp branch I'd used
> inet_socktop().
> inet_socktop() works like a charm.  I'm not exactly sure what's wrong
> with using inet_ntop() (or whether it's just called incorrectly in this
> case), but is there any reason not to use inet_socktop()?
>
> If not, I'll check in the attached.
>
> Regards,
>
> jah

> --- nmap_dns.cc.orig  2010-01-13 23:16:26.390625000 +0000
> +++ nmap_dns.cc       2010-01-13 23:04:00.812500000 +0000
> @@ -1345,7 +1345,6 @@
>  // Returns a list of known DNS servers
>  std::list<std::string> get_dns_servers() {
>    init_servs();
> -  char addrStr[INET6_ADDRSTRLEN];
>  
>    // If the user said --system-dns (!o.mass_dns), we should never return a list
>    // of servers.
> @@ -1354,8 +1353,7 @@
>    std::list<dns_server *>::iterator servI;
>    std::list<std::string> serverList;
>    for(servI = servs.begin(); servI != servs.end(); servI++) {
> -    inet_ntop((*servI)->addr.ss_family, (&(*servI)->addr),addrStr, sizeof(addrStr));  
> -    serverList.push_back(addrStr);
> +    serverList.push_back(inet_socktop((struct sockaddr_storage *) &(*servI)->addr));
>    }
>    return serverList;
>  }

That looks good, please commit it. The original code, from r16016, was
incorrect. It was giving the address of the beginning of the
sockaddr_storage structure when it should have been giving the address
of the sin_addr or sin6_addr member as appropriate.

Boy, there are a lot of ways to get a printable address in Nmap.
inet_ntoa, inet_ntop, inet_socktop, inet_ntop_both, inet_ntop_ez, and
getnameinfo are some that I can find. Ncat also has its own inet_socktop
and a getnameinfo wrapper called address_to_string. If someone wants a
nice easy project to do, seeing how many of these functions can be
removed and replaced with others would be good.

David Fifield
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