?
Solved

Access a server file using impersonation

Posted on 2006-06-19
13
Medium Priority
?
502 Views
Last Modified: 2008-08-26
I have to access an internal file from a web application and need to use impersonation to get access to the server.

I have not been sucessful so far, and the "help" files for .NET are somewhat lacking...

it's an asp.Net application with C# code behind.

Thank you,

Michelle
0
Comment
Question by:mnp13
  • 6
  • 3
10 Comments
 
LVL 12

Expert Comment

by:sumix
ID: 16940049
0
 

Author Comment

by:mnp13
ID: 17099544
please leave it active, I am still working on the project. thank you.
0
 

Author Comment

by:mnp13
ID: 17156530
It's not working and not giving me an error message or any indication of why...

it throws me to the "catch" at this line: impersonationContext =
                              ((System.Security.Principal.WindowsIdentity)User.Identity).Impersonate();
0
Concerto Cloud for Software Providers & ISVs

Can Concerto Cloud Services help you focus on evolving your application offerings, while delivering the best cloud experience to your customers? From DevOps to revenue models and customer support, the answer is yes!

Learn how Concerto can help you.

 
LVL 96

Expert Comment

by:Bob Learned
ID: 17159369
Can you show me how you are using this code?

Bob
0
 

Author Comment

by:mnp13
ID: 17160832
I'll post the section of code I"m useing on Monday, as it is on my work computer. Thanks!
0
 

Author Comment

by:mnp13
ID: 17167690
using System.Security.Principal;

...code...


                        System.Security.Principal.WindowsImpersonationContext impersonationContext;
                        impersonationContext =
                              ((System.Security.Principal.WindowsIdentity)User.Identity).Impersonate();
                  if (servPath.Equals("Null"))
                  {
                        this.hypServPDF.Enabled = false;
                        this.hypServPDF.Text = "not available";
                  }
                  else
                  {


                        this.hypServPDF.Enabled = true;
                        this.hypServPDF.Text = "Download";
                        this.hypServPDF.NavigateUrl = servPath.ToString();
                        this.hypServPDF.Target = "bill";



                  }
                        impersonationContext.Undo();
                  
0
 
LVL 96

Expert Comment

by:Bob Learned
ID: 17189742
Here is a class converted from VB.NET (untested):

using System;
using System.Runtime.InteropServices;
using System.Security.Principal;
using System.Security.Permissions;

public class WindowsImpersonator
{

  [DllImport("advapi32.dll", CharSet=CharSet.Auto)]
  private static extern bool LogonUser(string lpszUsername, string lpszDomain, string lpszPassword, int dwLogonType, int dwLogonProvider, ref IntPtr phToken);

  [DllImport("kernel32.dll")]
  private static extern int FormatMessage(int dwFlags, ref IntPtr lpSource, int dwMessageId, int dwLanguageId, ref string lpBuffer, int nSize, ref IntPtr Arguments);

  [DllImport("kernel32.dll", CharSet=CharSet.Auto)]
  private static extern bool CloseHandle(IntPtr handle);

  [DllImport("advapi32.dll", CharSet=CharSet.Auto)]
  private static extern bool DuplicateToken(IntPtr ExistingTokenHandle, int SECURITY_IMPERSONATION_LEVEL, ref IntPtr DuplicateTokenHandle);

  private WindowsImpersonationContext m_impersonatedUser;

  private static string GetErrorMessage(int errorCode)
  {
    int FORMAT_MESSAGE_ALLOCATE_BUFFER = 256;
    int FORMAT_MESSAGE_IGNORE_INSERTS = 512;
    int FORMAT_MESSAGE_FROM_SYSTEM = 4096;

    int messageSize = 255;
    string lpMsgBuf = "";
    int dwFlags = FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS;

    IntPtr ptrlpSource = IntPtr.Zero;
    IntPtr prtArguments = IntPtr.Zero;

    int retVal = FormatMessage(dwFlags, ref ptrlpSource, errorCode, 0, ref lpMsgBuf, messageSize, ref prtArguments);
    if (0 == retVal)
    {
      throw new Exception("Failed to format message for error code " + errorCode.ToString() + ". ");
    }
    return lpMsgBuf;
  }

  public void Impersonate(string domainName, string userName, string password)
  {
    const int LOGON32_PROVIDER_DEFAULT = 0;
    const int LOGON32_LOGON_INTERACTIVE = 2;
    const int SecurityImpersonation = 2;
    IntPtr tokenHandle = IntPtr.Zero;
    IntPtr dupeTokenHandle = IntPtr.Zero;
    try
    {
      bool returnValue = LogonUser(userName, domainName, password, LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT, ref tokenHandle);
      if (!returnValue)
      {
        int ret = Marshal.GetLastWin32Error();
        throw new Exception(string.Format("Error: [{0}] {1}", ret, GetErrorMessage(ret)));
      }
      bool retVal = DuplicateToken(tokenHandle, SecurityImpersonation, ref dupeTokenHandle);
      if (!retVal)
      {
        CloseHandle(tokenHandle);
        throw new Exception("Exception thrown in trying to duplicate token.");
      }
      WindowsIdentity newId = new WindowsIdentity(dupeTokenHandle);
      m_impersonatedUser = newId.Impersonate();
      if (tokenHandle != IntPtr.Zero)
      {
        CloseHandle(tokenHandle);
      }
      if (dupeTokenHandle != IntPtr.Zero)
      {
        CloseHandle(dupeTokenHandle);
      }
    }
    catch (Exception ex)
    {
      Console.WriteLine(("Exception occurred. " + ex.Message));
    }
  }

  public void Undo()
  {
    m_impersonatedUser.Undo();
  }

  public string CurrentName
  {
    get { return WindowsIdentity.GetCurrent().Name; }
  }

}

Bob
0
 

Author Comment

by:mnp13
ID: 17189883
That is about 10 miles over my head. where do I put that, and where do I put the file path it is suppoed to be accessing?
0
 
LVL 96

Accepted Solution

by:
Bob Learned earned 2000 total points
ID: 17191139
Sorry for the great distance.

Here are the steps:

1) Copy/paste that code into a class module

2) Create an instance of the class:

   WindowsImpersonator alias = new WindowsImpersonator();

3) Impersonate someone:

    alias.Impersonate("domain", "user", "password");

4) When your done Undo:

    alias.Undo();

5) The current name is here:

    string currentName = alias.CurrentName;

Bob
0
 

Author Comment

by:mnp13
ID: 17192855
ok, I'll give it a go...

I'm off of work until Monday, but I will try it and repond then.
0

Featured Post

Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Article by: Najam
Having new technologies does not mean they will completely replace old components.  Recently I had to create WCF that will be called by VB6 component.  Here I will describe what steps one should follow while doing so, please feel free to post any qu…
This article aims to explain the working of CircularLogArchiver. This tool was designed to solve the buildup of log file in cases where systems do not support circular logging or where circular logging is not enabled
this video summaries big data hadoop online training demo (http://onlineitguru.com/big-data-hadoop-online-training-placement.html) , and covers basics in big data hadoop .
This lesson discusses how to use a Mainform + Subforms in Microsoft Access to find and enter data for payments on orders. The sample data comes from a custom shop that builds and sells movable storage structures that are delivered to your property. …

578 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question