libcurl and ip resolution

Posted on 2006-05-22
Medium Priority
Last Modified: 2012-08-13
I'm using libcurl in my perl application to download some web sites. I need to know what IP address those web sites resolve to, to know the specific IP that my curl code is hitting. Is there any way to query the libcurl response to see what IP it actually hit, not just the domain?

The main reason for this is to know which load balanced server I'm hitting.

One option would be for me to get the IP address independently, but I wouldn't be guaranteed to get the same IP if the DNS rotates amongst a number. Or I could get the IP address first, then hit the IP address itself, but some domains require that you request the specific domain and not just the ip address.

Anyone have any other ideas?
Question by:timdr
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Expert Comment

ID: 16738709
do you need this permanently or for diagnosis ?
if you need it only for diagnosis, you could use a tool like Ethereal ( http://www.ethereal.com/ ) and view all HTTP connections.

There's lots of information on how to run it out there  too ( http://www.google.com/search?q=ethereal+tutorial+network )

Author Comment

ID: 16738835
I need it continuously, each time I make the request, for an application I have. So unfortunately no ethereal or anything like that. Needs to be part of the code basically.
LVL 51

Accepted Solution

ahoffmann earned 1500 total points
ID: 16740093
use Sys::Hostname;
use Socket;
$addr   = inet_ntoa(gethostbyname($host));

Author Comment

ID: 16743731
Getting the IP address this way doesn't guarantee that I'm getting the same IP that the libcurl download used does it?
LVL 51

Expert Comment

ID: 16744882
depends on the gethostbyname() function used by libcurl, i.g. it should be the same (except you have an ancient libc)

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