What's the best way, using C# or other .NET language, to determine if a file path string is on the local machine or a remote server?
It's possible to determine if a path string is UNC using the following:
new Uri(path).IsUnc
That works great for paths that start with C:\ or other drive letter, but what about paths like:
\\machinename\sharename\directory
\\10.12.34.56\sharename\directory
...where both refer to the local machine - these are UNC paths but are still local.
This is how I did it.
public static bool IsLocal(DirectoryInfo dir)
{
foreach (DriveInfo d in DriveInfo.GetDrives())
{
if (string.Compare(dir.Root.FullName, d.Name, StringComparison.OrdinalIgnoreCase) == 0) //[drweb86] Fix for different case.
{
return (d.DriveType != DriveType.Network);
}
}
throw new DriveNotFoundException();
}
Don't know if there's a more efficient way of doing this, but it seems to work for me:
IPAddress[] host;
IPAddress[] local;
bool isLocal = false;
host = Dns.GetHostAddresses(uri.Host);
local = Dns.GetHostAddresses(Dns.GetHostName());
foreach (IPAddress hostAddress in host)
{
if (IPAddress.IsLoopback(hostAddress))
{
isLocal = true;
break;
}
else
{
foreach (IPAddress localAddress in local)
{
if (hostAddress.Equals(localAddress))
{
isLocal = true;
break;
}
}
if (isLocal)
{
break;
}
}
}
.NET 3.5 version of Eric's answer with an extra check whether the host exists:
private bool IsLocalHost(string input)
{
IPAddress[] host;
//get host addresses
try { host = Dns.GetHostAddresses(input); }
catch (Exception) { return false; }
//get local adresses
IPAddress[] local = Dns.GetHostAddresses(Dns.GetHostName());
//check if local
return host.Any(hostAddress => IPAddress.IsLoopback(hostAddress) || local.Contains(hostAddress));
}
The following should work for mapped drives and for UNC paths.
private static bool IsLocalPath(String path)
{
if (!PathIsUNC(path))
{
return !PathIsNetworkPath(path);
}
Uri uri = new Uri(path);
return IsLocalHost(uri.Host); // Refer to David's answer
}
[DllImport("Shlwapi.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool PathIsNetworkPath(String pszPath);
[DllImport("Shlwapi.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool PathIsUNC(String pszPath);
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