Printing from ASP.NET to a network printer

Question

I need to send documents to a network printer (\myserver\myprinter). I'm using the System.Printing classes to print, and it works fine when it's from a Windows Service, but from an ASP.NET app, it's only able to print to local printers, not network printers. The error I'm getting is "Printer Name is not valid" This is what I'm using to get the printer name:

public string PrinterName
{
   using (LocalPrintServer server = new LocalPrintServer())
   return server.GetPrintQueue(@"\\myserver\myprinter");
}

What are my options here? Is this a permissions problem?

Answer 1

There are issues with credentials that you could solve by impersonation or elevating rights of the user the web app is running under.

However, we did it by adding the network printer as a printer on the server (add printer dialogue on server) and having the job sent to that printer.

We used the Printing.PrintDocument like so (Code in VB)....

Public Class SpecialReportPrintJob
  Inherits Printing.PrintDocument

Protected Overrides Sub OnBeginPrint(ByVal ev as Printing.PrintEventArgs)
  MyBase.OnBeginPrint(ev)

  Me.PrinterSettings.PrinterName = "PrinterNameUsedOnServer"

  'setup rest of stuff....
End Sub  
End Class
'And we then call it like so
Dim printSpecialReport as new SpecialReportPrintJob()
printSpecialReport.Print()

Answer 2

By default, an ASP.NET application runs on a special account with limited rights. Just enough to serve webpages, nothing more. So you'll have to configure the ASPNET user.

By contrast Windows services usually run under local System account (with high privileges)

Answer 3

The Network Printing from ASP.Net/C# can be done using:

If the Network is configured for Domain Users and Printer is added to print server:

• PrinterName to be defined as = "\\PrintServerIP_OR_Name\\PRINTERNAME" Example: PrinterSettings.PrinterName = "\\15.1.1.1\\prn001"
• Check the permission set on the Printer Access
• Which either be Domain Users or Everyone
• If Domain Users, then the C# code can be enclosed within the impersonation that can be used to call the print code which is as below:

/// <summary>
    /// Does the actual impersonation.
    /// </summary>
    /// <param name="userName">The name of the user to act as.</param>
    /// <param name="domainName">The domain name of the user to act as.</param>
    /// <param name="password">The password of the user to act as.</param>
    private void ImpersonateValidUser(
        string userName, 
        string domain, 
        string password )
    {
        WindowsIdentity tempWindowsIdentity = null;
        IntPtr token = IntPtr.Zero;
        IntPtr tokenDuplicate = IntPtr.Zero;

        try
        {
            if ( RevertToSelf() )
            {
                if ( LogonUser(
                    userName, 
                    domain, 
                    password, 
                    LOGON32_LOGON_INTERACTIVE,
                    LOGON32_PROVIDER_DEFAULT, 
                    ref token ) != 0 )
                {
                    if ( DuplicateToken( token, 2, ref tokenDuplicate ) != 0 )
                    {
                        tempWindowsIdentity = new WindowsIdentity( tokenDuplicate );
                        impersonationContext = tempWindowsIdentity.Impersonate();
                    }
                    else
                    {
                        throw new Win32Exception( Marshal.GetLastWin32Error() );
                    }
                }
                else
                {
                    throw new Win32Exception( Marshal.GetLastWin32Error() );
                }
            }
            else
            {
                throw new Win32Exception( Marshal.GetLastWin32Error() );
            }
        }
        finally
        {
            if ( token!= IntPtr.Zero )
            {
                CloseHandle( token );
            }
            if ( tokenDuplicate!=IntPtr.Zero )
            {
                CloseHandle( tokenDuplicate );
            }
        }
    }

    /// <summary>
    /// Reverts the impersonation.
    /// </summary>
    private void UndoImpersonation()
    {
        if ( impersonationContext!=null )
        {
            impersonationContext.Undo();
        }   
    }

    private WindowsImpersonationContext impersonationContext = null;

First make an call to impersonate the user and then call the print function that would look like below:

if(ImpersonateValidUser("username", "domain", "password"))
{
  PrintDetails();
  UndoImpersonation();
}