如何在HTTP处理程序ashx中将文件上传到网络路径？

Question

我尝试使用以下Silverlight应用程序代码将文件上传到网络路径：

public void ProcessRequest (HttpContext context) 
{
  //.....
  using (FileStream fs = File.Create(@"\\Server\Folder\" + filename))            
 {
   byte[] buffer = new byte[4096];
   int bytesRead;
   while ((bytesRead = context.Request.InputStream.Read(buffer, 0, buffer.Length)) != 0)
   {
      fs.Write(buffer, 0, bytesRead);
   }
 }
}

当我使用VS内置的Web服务器在调试模式下运行它时，它工作正常。 在SL端，我用url将此处理程序称为：

UriBuilder ub = new UriBuilder("http://localhost:38700/FileUpload.ashx");

然后，我将此应用程序发布到本地IIS，并将URL更改为http://localhost/Mysite/FileUpload.ashx

然后再次运行该应用程序。 它不再工作了，但是没有错误。

我猜这是因为调用File.Create的凭据不同。 所以我想在处理程序中使用特定的凭据将文件放置到目标位置。

如何对File.Create使用凭据？

Answer 1

我相信您将需要冒充用户。 下面的代码应该做到这一点。 本质上，您收集域，用户和密码并实例化ImpersonationMgr类。 然后调用BeginImpersonation方法。 之后，调用所需的相应WriteFile方法。 如果启用了模拟，则WriteFile方法将断言。 您可以对其他文件方法（例如删除和移动）遵循类似的模式。

public class ImpersonationMgr : IDisposable

  [DllImport("advapi32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
  public static extern bool LogonUser(String lpszUsername, String lpszDomain, String lpszPassword, int dwLogonType,
                                      int dwLogonProvider, out SafeTokenHandle phToken);

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

  private const int LOGON32_PROVIDER_DEFAULT = 0;
  private const int LOGON32_LOGON_NEW_CREDENTIALS = 9;

  private readonly string userName = string.Empty;
  private readonly string domainName = string.Empty;
  private readonly string password = string.Empty;

  private SafeTokenHandle safeTokenHandle = null;
  private WindowsImpersonationContext impersonatedUser = null;

  public ImpersonationMgr(string userName, string domainName, string password)
  {
     this.userName = userName;
     this.domainName = domainName;
     this.password = password;
  }

  public void BeginImpersonation()
  {
     bool returnValue = LogonUser(userName, domainName, password, LOGON32_LOGON_NEW_CREDENTIALS,
                                  LOGON32_PROVIDER_DEFAULT, out safeTokenHandle);
     if (returnValue == false)
     {
        int ret = Marshal.GetLastWin32Error();
        throw new System.ComponentModel.Win32Exception(ret);
     }

     impersonatedUser = WindowsIdentity.Impersonate(safeTokenHandle.DangerousGetHandle());
  }

  private void AssertImpersonationIsEnabled()
  {
     if(safeTokenHandle == null || impersonatedUser == null)
     {
        throw new UnauthorizedAccessException("You must call the BeginImpersonation method before attempting file write access.");
     }
  }

  public void WriteFile(string pathToFile, string fileContents)
  {
     AssertImpersonationIsEnabled();
     using (FileStream fileStream = File.Open(pathToFile, FileMode.CreateNew))
     {
        using (StreamWriter fileWriter = new StreamWriter(fileStream))
        {
           fileWriter.Write(fileContents);
        }
     }
  }

  public void WriteFile(string pathToFile, byte[] fileContents)
  {
     AssertImpersonationIsEnabled();
     using (FileStream fileStream = new FileStream(pathToFile, FileMode.Create))
     {
        fileStream .Write(fileContents, 0, fileContents.Length);
        fileStream .Flush();          
     }
  }

  public void Dispose()
  {
     Dispose(true);
     GC.SuppressFinalize(this);
  }
}

更新

   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);
      }
   }