Is it allowed to Substring IPHostEntry.HostName for Machine Name?

Question

Right now i have the requirement to find some PC's Hostname by his IP Address and i solved this problem with this function:

/// <summary>
/// Returns the DNS Name of IP Address without the Domain.
/// </summary>
public string GetDNSNameFromReverseLookUp(string ip)
{
    IPAddress hostIPAddress = IPAddress.Parse(ip);
    IPHostEntry hostInfo = Dns.GetHostEntry(hostIPAddress);
    return hostInfo.HostName.Substring(0, hostInfo.HostName.IndexOf('.'));
}

But i'm not happy with this substring() solution of the problem.

Is it allowed to use this function this way? Or do i have to fear some network issues in the future? Are there better (more secure) ways to get to the hostname without domain?

I'm looking for an more network secure solution, not another way to handle strings. As mentioned in the comments I fear a little bit, that not every OS returns the Hostname in the format:[Hostname].[Domainname].

The other way could be to split the string on dot(.) but that would be only as SECURE as this one :) — sachin, Aug 03 '16 at 08:09
I fear a little bit, that not every OS returns the Hostname in the format: `[Hostname].[Domainname]`. — Smartis has left SO again, Aug 03 '16 at 08:28

score 0 · Answer 1 · answered Aug 03 '16 at 08:26

0

You will get an error if pc are not joined to a domain. Since the (dot) is not found, and so the use of split function is the most reasonable. I've already checked.

answered Aug 03 '16 at 08:26

Adil

124
7

That's right but also not the responsibility of the function. – Smartis has left SO again Aug 03 '16 at 08:32

score -2 · Answer 2 · answered Aug 03 '16 at 08:10

-2

Try this

public string GetDNSNameFromReverseLookUp(string ip)
{
    IPAddress hostIPAddress = IPAddress.Parse(ip);
    IPHostEntry hostInfo = Dns.GetHostEntry(hostIPAddress);
    return hostInfo.HostName.Split('.')[0];
}

answered Aug 03 '16 at 08:10

Adil

124
7

Is it allowed to Substring IPHostEntry.HostName for Machine Name?

2 Answers2