C# - NetUseAdd from NetApi32.dll on Windows Server 2008 and IIS7

Question

I am attemping to use NetUseAdd to add a share that is needed by an application. My code looks like this.

[DllImport("NetApi32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
internal static extern uint NetUseAdd(
     string UncServerName,
     uint Level,
     IntPtr Buf,
     out uint ParmError);

...

USE_INFO_2 info = new USE_INFO_2();
info.ui2_local = null;
info.ui2_asg_type = 0xFFFFFFFF;
info.ui2_remote = remoteUNC;
info.ui2_username = username;
info.ui2_password = Marshal.StringToHGlobalAuto(password);
info.ui2_domainname = domainName;

IntPtr buf = Marshal.AllocHGlobal(Marshal.SizeOf(info));

try
{
    Marshal.StructureToPtr(info, buf, true);

    uint paramErrorIndex;
    uint returnCode = NetUseAdd(null, 2, buf, out paramErrorIndex);

    if (returnCode != 0)
    {
        throw new Win32Exception((int)returnCode);
    }
}
finally
{
    Marshal.FreeHGlobal(buf);
}

This works fine on our server 2003 boxes. But in attempting to move over to Server 2008 and IIS7 this doesnt work any more. Through liberal logging i have found that it hangs on the line Marshal.StructureToPtr(info, buf, true);

I have absolutely no idea why this is can anyone shed any light on it for tell me where i might look for more information?

Answer 1

The reason is:

You pulled the p/invoke signature off pinvoke.net and you didn't verify it. The fool who initially wrote this p/invoke sample code had no idea what he was doing and created one that "works" on 32-bit systems but does not work on 64-bit systems. He somehow turned a very simple p/invoke signature into some amazingly complicated mess and it spread like wildfire on the net.

The correct signature is:

    [DllImport( "NetApi32.dll", SetLastError = true, CharSet = CharSet.Unicode )]
    public static extern uint NetUseAdd(
         string UncServerName,
         UInt32 Level,
         ref USE_INFO_2 Buf,
         out UInt32 ParmError
        );

    [StructLayout( LayoutKind.Sequential, CharSet = CharSet.Unicode )]
    public struct USE_INFO_2
    {
        public string ui2_local;
        public string ui2_remote;
        public string ui2_password;
        public UInt32 ui2_status;
        public UInt32 ui2_asg_type;
        public UInt32 ui2_refcount;
        public UInt32 ui2_usecount;
        public string ui2_username;
        public string ui2_domainname;
    }

And your code should read:

USE_INFO_2 info = new USE_INFO_2();   
info.ui2_local = null;   
info.ui2_asg_type = 0xFFFFFFFF;   
info.ui2_remote = remoteUNC;   
info.ui2_username = username;   
info.ui2_password = password;
info.ui2_domainname = domainName;      

uint paramErrorIndex;   
uint returnCode = NetUseAdd(null, 2, ref info, out paramErrorIndex);   

if (returnCode != 0)   
{   
    throw new Win32Exception((int)returnCode);   
}

Hope this was of some help. I just spent half a day knee deep remote debugging someone elses trash code trying to figure out what was going on and it was this.

Answer 2

What kind of layout do you have for your struct? I believe the USE_INFO_2 needs to be [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)].

Also, have you tried just passing the structure by ref rather than needing to Marshal.StructureToPtr?

Answer 3

Good work! All I got nothing to see in my windows explorer. A few days later, ShellNotification came into my mind. This I had previously used for file icon association. And as I remembered there was also a trigger for NetShare add. Yes, right!

Afther a NetShareAdd you have to perform a SHChangeNotify from the shell32.dll.

ShellNotification.NotifyCreateDrive(info.ui2_local);

And this is the class i used for it:

public class ShellNotification
{     
    [DllImport("shell32.dll")]
    private static extern void SHChangeNotify(
        UInt32 wEventId,
        UInt32 uFlags,
        IntPtr dwItem1,
        IntPtr dwItem2);

    // Notify shell of change of file associations.
    public static void NotifyOfChange()
    {
        SHChangeNotify(
            (uint)ShellChangeNotificationEvents.SHCNE_ASSOCCHANGED,
            (uint)(ShellChangeNotificationFlags.SHCNF_IDLIST | ShellChangeNotificationFlags.SHCNF_FLUSHNOWAIT),
            IntPtr.Zero,
            IntPtr.Zero);
    }

    internal static void NotifyCreateDrive(string path) //path = "M:"
    {
        IntPtr strPtr = Marshal.StringToHGlobalUni(path);

        //A folder on the local computer is being shared via the network. SHCNF_IDLIST or SHCNF_PATHW must be specified in uFlags. dwItem1 contains the folder that is being shared. dwItem2 is not used and should be NULL.
        SHChangeNotify(
           (uint)ShellChangeNotificationEvents.SHCNE_NETSHARE,
           (uint)(ShellChangeNotificationFlags.SHCNF_IDLIST | ShellChangeNotificationFlags.SHCNF_PATHW),
           strPtr,
           IntPtr.Zero);

        //also, you need to make sure to free the unmanaged memory:
        Marshal.FreeHGlobal(strPtr);
    }

    [Flags]
    private enum ShellChangeNotificationEvents : uint
    {
        //The name of a nonfolder item has changed. SHCNF_IDLIST or  SHCNF_PATH must be specified in uFlags. dwItem1 contains the  previous PIDL or name of the item. dwItem2 contains the new PIDL or name of the item. 
        SHCNE_RENAMEITEM = 0x00000001,
        //A nonfolder item has been created. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the item that was created. dwItem2 is not used and should be NULL.
        SHCNE_CREATE = 0x00000002,
        //A nonfolder item has been deleted. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the item that was deleted. dwItem2 is not used and should be NULL.
        SHCNE_DELETE = 0x00000004,
        //A folder has been created. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the folder that was created. dwItem2 is not used and should be NULL.
        SHCNE_MKDIR = 0x00000008,
        //A folder has been removed. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the folder that was removed. dwItem2 is not used and should be NULL.
        SHCNE_RMDIR = 0x00000010,
        //Storage media has been inserted into a drive. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the root of the drive that contains the new media. dwItem2 is not used and should be NULL.
        SHCNE_MEDIAINSERTED = 0x00000020,
        //Storage media has been removed from a drive. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the root of the drive from which the media was removed. dwItem2 is not used and should be NULL.
        SHCNE_MEDIAREMOVED = 0x00000040,
        //A drive has been removed. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the root of the drive that was removed. dwItem2 is not used and should be NULL.
        SHCNE_DRIVEREMOVED = 0x00000080,
        //A drive has been added. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the root of the drive that was added. dwItem2 is not used and should be NULL.
        SHCNE_DRIVEADD = 0x00000100,
        //A folder on the local computer is being shared via the network. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the folder that is being shared. dwItem2 is not used and should be NULL.
        SHCNE_NETSHARE = 0x00000200,
        //A folder on the local computer is no longer being shared via the network. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the folder that is no longer being shared. dwItem2 is not used and should be NULL.
        SHCNE_NETUNSHARE = 0x00000400,
        //The attributes of an item or folder have changed. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the item or folder that has changed. dwItem2 is not used and should be NULL.
        SHCNE_ATTRIBUTES = 0x00000800,
        //The contents of an existing folder have changed, but the folder still exists and has not been renamed. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the folder that has changed. dwItem2 is not used and should be NULL. If a folder has been created, deleted, or renamed, use SHCNE_MKDIR, SHCNE_RMDIR, or SHCNE_RENAMEFOLDER, respectively, instead.
        SHCNE_UPDATEDIR = 0x00001000,
        //An existing nonfolder item has changed, but the item still exists and has not been renamed. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the item that has changed. dwItem2 is not used and should be NULL. If a nonfolder item has been created, deleted, or renamed, use SHCNE_CREATE, SHCNE_DELETE, or SHCNE_RENAMEITEM, respectively, instead.
        SHCNE_UPDATEITEM = 0x00002000,
        //The computer has disconnected from a server. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the server from which the computer was disconnected. dwItem2 is not used and should be NULL.
        SHCNE_SERVERDISCONNECT = 0x00004000,
        //An image in the system image list has changed. SHCNF_DWORD must be specified in uFlags. dwItem1 contains the index in the system image list that has changed. dwItem2 is not used and should be NULL.
        SHCNE_UPDATEIMAGE = 0x00008000,
        //A drive has been added and the Shell should create a new window for the drive. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the root of the drive that was added. dwItem2 is not used and should be NULL.
        SHCNE_DRIVEADDGUI = 0x00010000,
        //The name of a folder has changed. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the previous pointer to an item identifier list (PIDL) or name of the folder. dwItem2 contains the new PIDL or name of the folder.
        SHCNE_RENAMEFOLDER = 0x00020000,
        //The amount of free space on a drive has changed. SHCNF_IDLIST or SHCNF_PATH must be specified in uFlags. dwItem1 contains the root of the drive on which the free space changed. dwItem2 is not used and should be NULL.
        SHCNE_FREESPACE = 0x00040000,
        //Not currently used.
        SHCNE_EXTENDED_EVENT = 0x04000000,
        //A file type association has changed. SHCNF_IDLIST must be specified in the uFlags parameter. dwItem1 and dwItem2 are not used and must be NULL.
        SHCNE_ASSOCCHANGED = 0x08000000,
        //Specifies a combination of all of the disk event identifiers.
        SHCNE_DISKEVENTS = 0x0002381F,
        //Specifies a combination of all of the global event identifiers. 
        SHCNE_GLOBALEVENTS = 0x0C0581E0,
        //All events have occurred.
        SHCNE_ALLEVENTS = 0x7FFFFFFF,
        //The specified event occurred as a result of a system interrupt. As this value modifies other event values, it cannot be used alone.
        SHCNE_INTERRUPT = 0x80000000
    }

    private enum ShellChangeNotificationFlags
    {
        //dwItem1 and dwItem2 are the addresses of ITEMIDLIST structures that represent the item(s) affected by the change. Each ITEMIDLIST must be relative to the desktop folder. 
        SHCNF_IDLIST = 0x0000,
        //dwItem1 and dwItem2 are the addresses of null-terminated strings of maximum length MAX_PATH that contain the full path names of the items affected by the change.
        SHCNF_PATHA = 0x0001,
        //dwItem1 and dwItem2 are the addresses of null-terminated strings that represent the friendly names of the printer(s) affected by the change.
        SHCNF_PRINTERA = 0x0002,
        //The dwItem1 and dwItem2 parameters are DWORD values.
        SHCNF_DWORD = 0x0003,
        //like SHCNF_PATHA but unicode string
        SHCNF_PATHW = 0x0005,
        //like SHCNF_PRINTERA but unicode string
        SHCNF_PRINTERW = 0x0006,
        //?
        SHCNF_TYPE = 0x00FF,
        //The function should not return until the notification has been delivered to all affected components. As this flag modifies other data-type flags, it cannot by used by itself.
        SHCNF_FLUSH = 0x1000,
        //The function should begin delivering notifications to all affected components but should return as soon as the notification process has begun. As this flag modifies other data-type flags, it cannot by used  by itself.
   }
}

I hope to have others handed a welcome addition.