getting hostname or domain name from the ip address

[bluecoder]

Hi ,
I need a help regarding the socket programming i am doing .
I am trying to get the host or domain name from the ip address ..
e.g for the ip address 74.125.236.210 ... i should get www.google.com

I have tried twomethods for this .. like ..

WSADATA wsaData;
WSAStartup(MAKEWORD(2,0),&wsaData);
 
unsigned long ip     = inet_addr("74.125.236.210");
struct hostent *host = gethostbyaddr((const char FAR*)&ip,sizeof in_addr,0);

struct sockaddr_in sa;
	u_short port = 27015;
	sa.sin_family = AF_INET;
	sa.sin_addr.s_addr = inet_addr("74.125.236.210");
	sa.sin_port = htons(port);
	char host[1024];
	char service[20];
	getnameinfo( (struct sockaddr *) &sa, sizeof sa, host, sizeof host, service, sizeof service, 0);
	CString strTemp = host ; 

for all the two method i get

maa03s17-in-f18.1e100.net

instead of

www.google.com 

I am using winsock for this. ..
please help..thanks in advance ..

[bluecoder]

please give me some suggestion ..please .. I am not finding any thing on it ..

[guestgulkan]

Things are not always that easy on the internet.
servers are aliased, or redirected etc...
Big busy sites like www.google.com will be mirrored across several several servers to share the load - can you imagine how slooooow google would be if it ran on just one computer???

Here is what I mean -

C:\Windows\system32>ping -a www.google.com

Pinging www.l.google.com [173.194.66.103] with 32 bytes of data:
Reply from 173.194.66.103: bytes=32 time=41ms TTL=45
Reply from 173.194.66.103: bytes=32 time=33ms TTL=45
Reply from 173.194.66.103: bytes=32 time=33ms TTL=45
Reply from 173.194.66.103: bytes=32 time=32ms TTL=45

C:\Windows\system32>ping -a 173.194.66.103

Pinging we-in-f103.1e100.net [173.194.66.103] with 32 bytes of data:
Reply from 173.194.66.103: bytes=32 time=32ms TTL=45
Reply from 173.194.66.103: bytes=32 time=44ms TTL=45
Reply from 173.194.66.103: bytes=32 time=37ms TTL=45
Reply from 173.194.66.103: bytes=32 time=32ms TTL=45

But if you put 173.194.66.103 in your internet browser - you will see the Google
website.

[bluecoder]

Thanks guestgulkan ... ...
but is there no way to get the url using the ip address ..or domain name using the ip address.

[guestgulkan]

There is the
host->h_aliases[0] field ot the hostent structure - this aliases field is an array of pointers to alternative names for the site (So you will probably find www.google.com in the first one. (h_aliases[0])
so

cout << host->h_aliases[0]; //check the first alternative name.

In truth - the h_name of the hostent is the official name, and the aliases are just alternatives (if they are any)

[bluecoder]

thanks guestgulkan ..
but when i put

 strTemp = host->h_aliases[0];
	  strTemp = host->h_aliases[1];
	  strTemp = host->h_aliases[2];

strTemp is empty always ..for the array 0 , 1 , 2 ..
is there any other way or can you tell me as why this array is empty .

[bluecoder]

can any one let me know the answer ... I am really stuck on this one.
thanks in advance ..

[guestgulkan]

There is nothing to get stuck about.

The h_aliases is a pointer to a - null terminated array of char*-
Unfortunately there is no field in the hostent structure that tels you how
many aliases they are - it is possible for there to be no aliases - so you cannot
really do strTemp = host->h_aliases[2] directly.

You can loop around the h_aliases array until you reach the NULL pointer end marker. One possible loop style could be:

 for (int count = 0;  host->h_aliases[count] !=0; ++count )
{
       //do whatever you want with the alias string
     //in this case I'm just going to show on screen
      cout << host->h_aliases[count] << endl;
}

[bluecoder]

executing the code you gave me .. still

 for (int count = 0;  host->h_aliases[count] !=0; ++count )
{
       //do whatever you want with the alias string
     //in this case I'm just going to show on screen
      cout << host->h_aliases[count] << endl;
}

still
host->haliases[count] is empty ..

[guestgulkan]

maybe they aren't any aliases - a site does not have to have a set of alias names.