How to provide user name and password when connecting to a network share
When connecting to a network share for which the current user (in my case, a network enabled service user) has no rights, name and password have to be provided.
I know how to do this with Win32 functions (the WNet* family from mpr.dll ), but would like to do it with .Net (2.0) functionality.
What options are available?
Maybe some more information helps:
You can either change the thread identity, or P/Invoke WNetAddConnection2. I prefer the latter, as I sometimes need to maintain multiple credentials for different locations. I wrap it into an IDisposable and call WNetCancelConnection2 to remove the creds afterwards (avoiding the multiple usernames error):
using (new NetworkConnection(@"serverread", readCredentials))
using (new NetworkConnection(@"server2write", writeCredentials)) {
File.Copy(@"serverreadfile", @"server2writefile");
}
I liked Mark Brackett's answer so much that I did my own quick implementation. Here it is if anyone else needs it in a hurry:
public class NetworkConnection : IDisposable
{
string _networkName;
public NetworkConnection(string networkName,
NetworkCredential credentials)
{
_networkName = networkName;
var netResource = new NetResource()
{
Scope = ResourceScope.GlobalNetwork,
ResourceType = ResourceType.Disk,
DisplayType = ResourceDisplaytype.Share,
RemoteName = networkName
};
var userName = string.IsNullOrEmpty(credentials.Domain)
? credentials.UserName
: string.Format(@"{0}{1}", credentials.Domain, credentials.UserName);
var result = WNetAddConnection2(
netResource,
credentials.Password,
userName,
0);
if (result != 0)
{
throw new Win32Exception(result, "Error connecting to remote share");
}
}
~NetworkConnection()
{
Dispose(false);
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
protected virtual void Dispose(bool disposing)
{
WNetCancelConnection2(_networkName, 0, true);
}
[DllImport("mpr.dll")]
private static extern int WNetAddConnection2(NetResource netResource,
string password, string username, int flags);
[DllImport("mpr.dll")]
private static extern int WNetCancelConnection2(string name, int flags,
bool force);
}
[StructLayout(LayoutKind.Sequential)]
public class NetResource
{
public ResourceScope Scope;
public ResourceType ResourceType;
public ResourceDisplaytype DisplayType;
public int Usage;
public string LocalName;
public string RemoteName;
public string Comment;
public string Provider;
}
public enum ResourceScope : int
{
Connected = 1,
GlobalNetwork,
Remembered,
Recent,
Context
};
public enum ResourceType : int
{
Any = 0,
Disk = 1,
Print = 2,
Reserved = 8,
}
public enum ResourceDisplaytype : int
{
Generic = 0x0,
Domain = 0x01,
Server = 0x02,
Share = 0x03,
File = 0x04,
Group = 0x05,
Network = 0x06,
Root = 0x07,
Shareadmin = 0x08,
Directory = 0x09,
Tree = 0x0a,
Ndscontainer = 0x0b
}
Today 7 years later I'm facing the same issue and I'd like to share my version of the solution.
It is copy & paste ready :-) Here it is:
Step 1
In your code (whenever you need to do something with permissions)
ImpersonationHelper.Impersonate(domain, userName, userPassword, delegate
{
//Your code here
//Let's say file copy:
if (!File.Exists(to))
{
File.Copy(from, to);
}
});
Step 2
The Helper file which does a magic
using System;
using System.Runtime.ConstrainedExecution;
using System.Runtime.InteropServices;
using System.Security;
using System.Security.Permissions;
using System.Security.Principal;
using Microsoft.Win32.SafeHandles;
namespace BlaBla
{
public sealed class SafeTokenHandle : SafeHandleZeroOrMinusOneIsInvalid
{
private SafeTokenHandle()
: base(true)
{
}
[DllImport("kernel32.dll")]
[ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
[SuppressUnmanagedCodeSecurity]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool CloseHandle(IntPtr handle);
protected override bool ReleaseHandle()
{
return CloseHandle(handle);
}
}
public class ImpersonationHelper
{
[DllImport("advapi32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
private static extern bool LogonUser(String lpszUsername, String lpszDomain, String lpszPassword,
int dwLogonType, int dwLogonProvider, out SafeTokenHandle phToken);
[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
private extern static bool CloseHandle(IntPtr handle);
[PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
public static void Impersonate(string domainName, string userName, string userPassword, Action actionToExecute)
{
SafeTokenHandle safeTokenHandle;
try
{
const int LOGON32_PROVIDER_DEFAULT = 0;
//This parameter causes LogonUser to create a primary token.
const int LOGON32_LOGON_INTERACTIVE = 2;
// Call LogonUser to obtain a handle to an access token.
bool returnValue = LogonUser(userName, domainName, userPassword,
LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT,
out safeTokenHandle);
//Facade.Instance.Trace("LogonUser called.");
if (returnValue == false)
{
int ret = Marshal.GetLastWin32Error();
//Facade.Instance.Trace($"LogonUser failed with error code : {ret}");
throw new System.ComponentModel.Win32Exception(ret);
}
using (safeTokenHandle)
{
//Facade.Instance.Trace($"Value of Windows NT token: {safeTokenHandle}");
//Facade.Instance.Trace($"Before impersonation: {WindowsIdentity.GetCurrent().Name}");
// Use the token handle returned by LogonUser.
using (WindowsIdentity newId = new WindowsIdentity(safeTokenHandle.DangerousGetHandle()))
{
using (WindowsImpersonationContext impersonatedUser = newId.Impersonate())
{
//Facade.Instance.Trace($"After impersonation: {WindowsIdentity.GetCurrent().Name}");
//Facade.Instance.Trace("Start executing an action");
actionToExecute();
//Facade.Instance.Trace("Finished executing an action");
}
}
//Facade.Instance.Trace($"After closing the context: {WindowsIdentity.GetCurrent().Name}");
}
}
catch (Exception ex)
{
//Facade.Instance.Trace("Oh no! Impersonate method failed.");
//ex.HandleException();
//On purpose: we want to notify a caller about the issue /Pavel Kovalev 9/16/2016 2:15:23 PM)/
throw;
}
}
}
}
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