Replace an IP-Address by DNS name

[ziwo]

Hi,

I have to parse a huge html file and should replace every occurrence of an IP address by their DNS name. So, during the run I should be able to do a nslookup (or similar).

I can imagine also a two step version:
extract the IP adresses first and create a lookup table
<IP> <DNS name>
<IP> <DNS name>
...
and use this table for replacing the IP addresses in the html file (to prevent the nslookup during the script run).

I'm not sure if awk is my solution.

Any help or pointer is verry welcome.

- ziwo

 

[CaKiwi]

Something like this might work. You would need to pass appropriate flags to nslookup and extract the DNS name out of the dns array.

{
match($0,/[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/)
while (RSTART) {
ip = substr($0,RSTART,RLENGTH)
"nslookup " ip | getline dns
sub(ip,dns)
match($0,/[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/)
}
}

CaKiwi