Not so cool name resolution

This takes an input of a machine name or an IP address, and checks to see if it exists and presents the name resolution. I included the script and the HTML page.

The coolest part of this (for me) was getting the name resolution down to one line. I couldn't have put this togther without bastardoperator and the other monks...

use CGI qw(:standard);


print header();
print start_html('Resolved');
&resolve();
print param('xinput')." resolved to $new";
print end_html;

#To resolve host names (xname) or IP(xip)...

sub resolve{
    if (param('xinput')=~/^\D/){ # if begins with a letter assume it's
+ a name
        $new=join('.',(unpack("C4", gethostbyname(param('xinput')))));
    }elsif (param('xinput')=~/^\d/){ # if begins with a number assume 
+it's an IP
        $new=gethostbyaddr(pack("C4", (split(/\./, param('xinput')))),
+ AF_INET);
    }
    if (($new eq null)||($new eq "")){
        print "Could not resolve.\n"; 
        die "Could not resolve.\n";
    }
}


print "<p><a href=".referer().'>back</a></p>';
[download]

Resolver.htm

<HTML>
<HEAD>
<TITLE>Name Resolution</TITLE>
</HEAD>
<BODY>
<FORM ACTION=scripts/resolver.pl method=post>
<P>Enter an IP address or Machine name:<BR>
<INPUT NAME=xinput VALUE=""></P>
<P><INPUT TYPE=SUBMIT value="Resolve">
</FORM>
</BODY>
</HTML>
[download]

Comment on Not so cool name resolution Select or Download Code

Replies are listed 'Best First'.
RE: Not so cool name resolution by myocom (Deacon) on Sep 15, 2000 at 00:12 UTC
Speaking of name resolution, here's a handy little one-liner: `perl -MSocket -e"print scalar gethostbyaddr(inet_aton(shift),1)"` Note: This is Win32-style `-e` quoting--change it if you need to for your particular system. For that matter, this is untested on any other system, though I suspect it works fine.	[reply] [d/l] [select]
RE: Not so cool name resolution by Fastolfe (Vicar) on Sep 14, 2000 at 23:45 UTC
You should not assume that every hostname starting with a number is an IP address. If you're going to do a regexp, why not go all the way: `/^\d+(\.\d+){3}$/` It's also common practice to examine the last part of the domain, since this must be alphabetic for hostnames: `/\.\d+$/` Don't just do `/\d$/`, because "www3" is a valid hostname, though "www.3" is not.	[reply] [d/l] [select]