| Platform SDK: Windows Networking |
The WNetOpenEnum function starts an enumeration of network resources or existing connections. You can continue the enumeration by calling the WNetEnumResource function.
DWORD WNetOpenEnum( DWORD dwScope, // scope of enumeration DWORD dwType, // resource types to list DWORD dwUsage, // resource usage to list LPNETRESOURCE lpNetResource, // resource structure LPHANDLE lphEnum // enumeration handle buffer );
| Value | Meaning |
|---|---|
| RESOURCE_CONNECTED | Enumerate all currently connected resources. The function ignores the dwUsage parameter. For more information, see the following Remarks section. |
| RESOURCE_CONTEXT | Enumerate only resources in the network context of the caller. Specify this value for a Network Neighborhood view. The function ignores the dwUsage parameter. |
| RESOURCE_GLOBALNET | Enumerate all resources on the network. |
| RESOURCE_REMEMBERED | Enumerate all remembered (persistent) connections. The function ignores the dwUsage parameter. |
| Value | Meaning |
|---|---|
| RESOURCETYPE_ANY | All resources. This value cannot be combined with RESOURCETYPE_DISK or RESOURCETYPE_PRINT. |
| RESOURCETYPE_DISK | All disk resources. |
| RESOURCETYPE_PRINT | All print resources. |
If a network provider cannot distinguish between print and disk resources, it can enumerate all resources.
| Value | Meaning |
|---|---|
| 0 | All resources. |
| RESOURCEUSAGE_CONNECTABLE | All connectable resources. |
| RESOURCEUSAGE_CONTAINER | All container resources. |
| RESOURCEUSAGE_ATTACHED | Setting this value forces WNetOpenEnum to fail if the user is not authenticated. The function fails even if the network allows enumeration without authentication. |
| RESOURCEUSAGE_ALL | Setting this value is equivalent to setting RESOURCEUSAGE_CONNECTABLE, RESOURCEUSAGE_CONTAINER, and RESOURCEUSAGE_ATTACHED. |
This parameter is ignored unless the dwScope parameter is equal to RESOURCE_GLOBALNET. For more information, see the following Remarks section.
If this parameter is NULL, the root of the network is assumed. (The system organizes a network as a hierarchy; the root is the topmost container in the network.)
If this parameter is not NULL, it must point to a NETRESOURCE structure. This structure can be filled in by the application or it can be returned by a call to the WNetEnumResource function. The NETRESOURCE structure must specify a container resource; that is, the RESOURCEUSAGE_CONTAINER value must be specified in the dwUsage parameter.
To enumerate all network resources, an application can begin the enumeration by calling WNetOpenEnum with the lpNetResource parameter set to NULL, and then use the returned handle to call WNetEnumResource to enumerate resources. If one of the resources in the NETRESOURCE array returned by the WNetEnumResource function is a container resource, you can call WNetOpenEnum to open the resource for further enumeration.
If the function succeeds, the return value is NO_ERROR.
If the function fails, the return value can be one of the following error codes.
| Value | Meaning |
|---|---|
| ERROR_NOT_CONTAINER | The lpNetResource parameter does not point to a container. |
| ERROR_INVALID_PARAMETER | Either the dwScope or the dwType parameter is invalid, or there is an invalid combination of parameters. |
| ERROR_NO_NETWORK | The network is unavailable. |
| ERROR_EXTENDED_ERROR | A network-specific error occurred. To obtain a description of the error, call the WNetGetLastError function. |
Windows NT/Windows 2000: If the dwScope parameter is equal to RESOURCE_CONNECTED, a network connection made using the Microsoft LAN Manager network is omitted from the enumeration if the connection was made by an application running in a different logon session than the application calling the WNetOpenEnum function. This is because connections made using Microsoft LAN Manager are visible only to applications running in the same logon session as the application that made the connection. (To include the connection in the enumeration, it is not sufficient for the application to be running in the user account that created the connection.)
The exact interpretation of RESOURCE_CONTEXT in the dwScope parameter depends on the networks installed on the machine.
The WNetOpenEnum function is used to begin enumeration of the resources in a single container. The following examples show the hierarchical structure of a Microsoft LAN Manager network and a Novell Netware network and identify the containers.
LanMan (container, in this case the provider)
ACCOUNTING (container, in this case the domain)
\\ACCTSPAY (container, in this case the server)
PAYFILES (disk)
LASERJET (print)
Netware (container, in this case the provider)
MARKETING (container, in this case the server)
SYS (disk, first one on any Netware server)
ANOTHERVOLUME (disk)
LASERJET (print)
For a code sample that illustrates an application-defined function that enumerates all the resources on a network, see Enumerating Network Resources.
Windows NT/2000: Requires Windows NT 3.1 or later.
Windows 95/98: Requires Windows 95 or later.
Header: Declared in Winnetwk.h.
Library: Use Mpr.lib.
Unicode: Implemented as Unicode and ANSI versions on Windows NT/2000.
Windows Networking (WNet) Overview, Windows Networking Functions, NETRESOURCE, WNetCloseEnum, WNetEnumResource