Platform SDK: Windows Networking

WNetUseConnection

The WNetUseConnection function makes a connection to a network resource. The function can redirect a local device to a network resource.

The WNetUseConnection function is similar to the WNetAddConnection3 function. The main difference is that WNetUseConnection can automatically select an unused local device to redirect to the network resource.

Windows NT/2000: The parameter order is as follows.

DWORD WNetUseConnection(
  HWND hwndOwner,              // owner window
  LPNETRESOURCE lpNetResource, // connection details
  LPCTSTR lpUserID,            // user
  LPCTSTR lpPassword,          // password
  DWORD dwFlags,               // connection options
  LPTSTR lpAccessName,         // buffer for system requests
  LPDWORD lpBufferSize,        // buffer size
  LPDWORD lpResult             // receives connection information
);

Windows 95/98: The lpUserID and lpPassword parameters are in reverse order from the order used on Windows NT/Windows 2000. Therefore, the parameter order is as follows.

DWORD WNetUseConnection(
  HWND hwndOwner,               
  LPNETRESOURCE lpNetResource,  
  LPCTSTR lpPassword,           
  LPCTSTR lpUserID,             
  DWORD dwFlags,                
  LPTSTR lpAccessName,          
  LPDWORD lpBufferSize,         
  LPDWORD lpResult              
);

Parameters

hwndOwner

[in] Specifies the handle to a window that the provider of network resources can use as an owner window for dialog boxes. Use this parameter if you set the CONNECT_INTERACTIVE value in the dwFlags parameter.

lpNetResource

[in] Pointer to a NETRESOURCE structure that specifies details of the proposed connection. The structure contains information about the network resource, the local device, and the network resource provider.

You must specify the following members of the NETRESOURCE structure.

Member Description

dwType Specifies the type of resource to connect to.
It is most efficient to specify a resource type in this member, such as RESOURCETYPE_DISK or RESOURCETYPE_PRINT. However, if the lpLocalName member is NULL, or if it points to an empty string and CONNECT_REDIRECT is not set, dwType can be RESOURCETYPE_ANY.

This method works only if the function does not automatically choose a device to redirect to the network resource.

lpLocalName Pointer to a null-terminated string that specifies the name of a local device to be redirected, such as "F:" or "LPT1". The string is treated in a case-insensitive manner.
If the string is empty, or if lpLocalName is NULL, a connection to the network occurs without redirection.

If the CONNECT_REDIRECT value is set in the dwFlags parameter, or if the network requires a redirected local device, the function chooses a local device to redirect and returns the name of the device in the lpAccessName parameter.

lpRemoteName Pointer to a null-terminated string that specifies the network resource to connect to. The string can be up to MAX_PATH characters in length, and it must follow the network provider's naming conventions.

lpProvider Pointer to a null-terminated string that specifies the network provider to connect to. If lpProvider is NULL, or if it points to an empty string, the operating system attempts to determine the correct provider by parsing the string pointed to by the lpRemoteName member.
If this member is not NULL, the operating system attempts to make a connection only to the named network provider.

You should set this member only if you know the network provider you want to use. Otherwise, let the operating system determine which provider the network name maps to.

Member	Description
dwType	Specifies the type of resource to connect to. It is most efficient to specify a resource type in this member, such as RESOURCETYPE_DISK or RESOURCETYPE_PRINT. However, if the lpLocalName member is NULL, or if it points to an empty string and CONNECT_REDIRECT is not set, dwType can be RESOURCETYPE_ANY. This method works only if the function does not automatically choose a device to redirect to the network resource.
lpLocalName	Pointer to a null-terminated string that specifies the name of a local device to be redirected, such as "F:" or "LPT1". The string is treated in a case-insensitive manner. If the string is empty, or if lpLocalName is NULL, a connection to the network occurs without redirection. If the CONNECT_REDIRECT value is set in the dwFlags parameter, or if the network requires a redirected local device, the function chooses a local device to redirect and returns the name of the device in the lpAccessName parameter.
lpRemoteName	Pointer to a null-terminated string that specifies the network resource to connect to. The string can be up to MAX_PATH characters in length, and it must follow the network provider's naming conventions.
lpProvider	Pointer to a null-terminated string that specifies the network provider to connect to. If lpProvider is NULL, or if it points to an empty string, the operating system attempts to determine the correct provider by parsing the string pointed to by the lpRemoteName member. If this member is not NULL, the operating system attempts to make a connection only to the named network provider. You should set this member only if you know the network provider you want to use. Otherwise, let the operating system determine which provider the network name maps to.

The WNetUseConnection function ignores the other members of the NETRESOURCE structure. For more information, see the descriptions following for the dwFlags parameter.

lpUserID

[in] Pointer to a constant null-terminated string that specifies a user name for making the connection.

If lpUserID is NULL, the function uses the default user name. (The user context for the process provides the default user name.)

The lpUserID parameter is specified when users want to connect to a network resource for which they have been assigned a user name or account other than the default user name or account.

The user-name string represents a security context. It may be specific to a network provider.

lpPassword

[in] Pointer to a constant null-terminated string that specifies a password to be used in making the network connection.

If lpPassword is NULL, the function uses the current default password associated with the user specified by lpUserID.

If lpPassword points to an empty string, the function does not use a password.

If the connection fails because of an invalid password and the CONNECT_INTERACTIVE value is set in the dwFlags parameter, the function displays a dialog box asking the user to type the password.

dwFlags

[in] Specifies a DWORD value that contains a set of bit flags describing the connection. This parameter can be any combination of the following values.

Value	Meaning
CONNECT_INTERACTIVE	If this flag is set, the operating system may interact with the user for authentication purposes.
CONNECT_PROMPT	This flag instructs the system not to use any default settings for user names or passwords without offering the user the opportunity to supply an alternative. This flag is ignored unless CONNECT_INTERACTIVE is also set.
CONNECT_REDIRECT	This flag forces the redirection of a local device when making the connection. If the lpLocalName member of NETRESOURCE specifies a local device to redirect, this flag has no effect, because the operating system still attempts to redirect the specified device. When the operating system automatically chooses a local device, the lpAccessName parameter must point to a return buffer and the dwType member must not be equal to RESOURCETYPE_ANY. If this flag is not set, a local device is automatically chosen for redirection only if the network requires a local device to be redirected.
CONNECT_UPDATE_PROFILE	This flag instructs the operating system to store the network resource connection. If this bit flag is set, the operating system automatically attempts to restore the connection when the user logs on. The system remembers only successful connections that redirect local devices. It does not remember connections that are unsuccessful or deviceless connections. (A deviceless connection occurs when lpLocalName is NULL or when it points to an empty string.) If this bit flag is clear, the operating system does not automatically restore the connection at logon.

lpAccessName

[out] Pointer to a buffer that receives system requests on the connection.

If the lpLocalName member of the NETRESOURCE structure specifies a local device, this buffer is optional, and will have the local device name copied into it. If lpLocalName does not specify a device and the network requires a local device redirection, or if the CONNECT_REDIRECT value is set, this buffer is required and the name of the redirected local device is returned here.

Otherwise, the name copied into the buffer is that of a remote resource. If specified, this buffer must be at least as large as the string pointed to by the lpRemoteName member.

lpBufferSize

[in/out] Pointer to a variable that specifies the size, in characters, of the lpAccessName buffer. If the call fails because the buffer is not large enough, the function returns the required buffer size in this location.

lpResult

[out] Pointer to a variable that receives additional information about the connection. This parameter can be the following value.

Value	Meaning
CONNECT_LOCALDRIVE	If this flag is set, the connection was made using a local device redirection. If the lpAccessName parameter points to a buffer, the local device name is copied to the buffer.

Return Values

If the function succeeds, the return value is NO_ERROR.

If the function fails, the return value is one of the following error codes.

Value	Meaning
ERROR_ACCESS_DENIED	Access to the network resource was denied.
ERROR_ALREADY_ASSIGNED	The local device specified by the lpLocalName member is already connected to a network resource.
ERROR_BAD_DEVICE	The value specified by lpLocalName is invalid.
ERROR_BAD_NET_NAME	The value specified by the lpRemoteName member is not acceptable to any network resource provider because the resource name is invalid, or because the named resource cannot be located.
ERROR_BAD_PROVIDER	The value specified by the lpProvider member does not match any provider.
ERROR_CANCELLED	The attempt to make the connection was canceled by the user through a dialog box from one of the network resource providers, or by a called resource.
ERROR_EXTENDED_ERROR	A network-specific error occurred. To obtain a description of the error, call the WNetGetLastError function.
ERROR_INVALID_ADDRESS	The caller passed in a pointer to a buffer that could not be accessed.
ERROR_INVALID_PARAMETER	This error is a result of one of the following conditions: The lpRemoteName member is NULL. In addition, lpAccessName is not NULL, but lpBufferSize is either NULL or points to zero. The dwType member is neither RESOURCETYPE_DISK nor RESOURCETYPE_PRINT. In addition, either CONNECT_REDIRECT is set in dwFlags and lpLocalName is NULL, or the connection is to a network that requires the redirecting of a local device.
ERROR_INVALID_PASSWORD	The specified password is invalid and the CONNECT_INTERACTIVE flag is not set.
ERROR_MORE_DATA	The lpAccessName buffer is too small. If a local device is redirected, the buffer needs to be large enough to contain the local device name. Otherwise, the buffer needs to be large enough to contain either the string pointed to by lpRemoteName, or the name of the connectable resource whose alias is pointed to by lpRemoteName. If this error is returned, then no connection has been made.
ERROR_NO_MORE_ITEMS	The operating system cannot automatically choose a local redirection because all the valid local devices are in use.
ERROR_NO_NET_OR_BAD_PATH	The operation could not be completed, either because a network component is not started, or because the specified resource name is not recognized.
ERROR_NO_NETWORK	The network is unavailable.

Requirements

  Windows NT/2000: Requires Windows NT 4.0 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.

WNetUseConnection

Parameters

Return Values

Requirements

See Also