Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 24 Mar 2003 01:32:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 24 Mar 2003 01:32:24 -0500 Received: from cimice4.netroute.cz ([212.71.168.94]:61638 "EHLO vagabond.cybernet.cz") by vger.kernel.org with ESMTP id ; Mon, 24 Mar 2003 01:32:22 -0500 Date: Mon, 24 Mar 2003 07:43:28 +0100 From: Jan Hudec To: linux-kernel@vger.kernel.org, kernelnewbies@nl.linux.org Subject: Re: GETHOSTBYNAME() Message-ID: <20030324064328.GE8167@vagabond> Mail-Followup-To: Jan Hudec , linux-kernel@vger.kernel.org, kernelnewbies@nl.linux.org References:

Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.3i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2895 Lines: 75 On Mon, Mar 24, 2003 at 10:25:11AM +0530, Prasad wrote: > > hi, > i dont think there is one similar to gethostbyname in the > kernel-space. I do think so because most of the work done by > gethostbyname is based on the nameservices and is generally not required > in the kernel-space. Implementing it should not be that big a problem. > once you have the IP of the name server (/etc/resolve.conf???) you can > always connect to it and get the IP of the given host. Implementing it is a big problem, since gethostbyname usualy means a DNS lookup. Best way to do it in kernel is call_usermode_helper('/sbin/khost') and call gethostbyname in there. > On Mon, 24 Mar 2003, shesha bhushan wrote: > > > Hi All > > I am trying to find the gethostbyname() equivalent function in kernel space. > > Does any one know that. > > The reason is... > > I am using UDP to transfer data from one machine to another. It is not one > > time transfer. Once I get a message from machine A; I need to send some > > message back to Machine A from Machine B. For that I was using the following > > lines in user space program. I need to do the same in kernel space. Could > > any one help me out in this. > > > > struct hostent *data; > > struct sockaddr_in server; > > int sock; > > > > sock = socket(AF_INET, SOCK_DGRAM , 0) > > > > /* binding and all are done here */ > > > > data = gethostbyname("158.168.1.1"); However as long as you are resolving IP address, you should not ask for gethostbyname. You should ask for inet_aton, which does exist (the name was mentioned in some list (linux-kernel or this one) not long ago, but I do not remember it). > > memcpy (&server.sin_addrs, data->h_addr, data->h_length); > > retval = sendto(sock,msg,sizeof(msg), 0, (struct sockaddr *) &server, > > sizeof server); > > > > > > Thanking You > > Shesha > > > > _________________________________________________________________ > > Cricket - World Cup 2003 http://server1.msn.co.in/msnspecials/worldcup03/ > > News, Views and Match Reports. > > > > - > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ > > > > -- > Failure is not an option > > -- > Kernelnewbies: Help each other learn about the Linux kernel. > Archive: http://mail.nl.linux.org/kernelnewbies/ > FAQ: http://kernelnewbies.org/faq/ > ------------------------------------------------------------------------------- Jan 'Bulb' Hudec - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/