NdisReadNetworkAddress function (ndis.h)

Article
04/18/2022

The NdisReadNetworkAddress function returns the software-configurable network address that was stored in the registry for a NIC when it was installed in the machine.

Syntax

void NdisReadNetworkAddress(
  [out] PNDIS_STATUS Status,
  [out] PVOID        *NetworkAddress,
  [out] PUINT        NetworkAddressLength,
  [in]  NDIS_HANDLE  ConfigurationHandle
);

Parameters

[out] Status

A pointer to a caller-supplied variable in which this function returns the status of the call as one of the following:

NDIS_STATUS_SUCCESS

The caller can use the address returned at NetworkAddress for the NIC.

NDIS_STATUS_FAILURE

There was no NIC address information available in the caller's registry Parameters key or the value stored was not a string.

[out] NetworkAddress

A pointer to a caller-supplied variable in which this function returns a pointer to a buffer that contains the network address (typically the MAC address), stored as a sequence of byte integers, if the call is successful.

[out] NetworkAddressLength

A pointer to a caller-supplied variable in which this function returns the number of bytes that are returned at NetworkAddress.

[in] ConfigurationHandle

The configuration handle returned by the NdisOpenConfigurationEx function.

Return value

None

Remarks

NdisReadNetworkAddress searches the registry Parameters key designated by the given ConfigurationHandle for the keyword NetworkAddress, converts the value of this string-type entry into a sequence of byte integers, and stores the requested information internally. The storage that NDIS allocates for such an address remains valid until the miniport driver calls the NdisCloseConfiguration function, which frees the memory.

The caller cannot use the variable at NetworkAddress as a pointer unless NdisReadNetworkAddress returns NDIS_STATUS_SUCCESS at Status.

The installation program for a NIC that supports software-configurable network addressing should store a value entry named with the NetworkAddress keyword in the HKLM\System\CurrentControlSet\Control\Class{4d36e972...}\00xx key of the registry.

A NIC installer usually stores the value of a NetworkAddress entry in the registry as a string of hexadecimal digits. Optionally, an installer can store such an address as a string of paired digits, with each pair separated from the next by a hyphen. NdisReadNetworkAddress discards hyphens and converts each such pair into a single byte.

In either form, NdisReadNetworkAddress converts the address specified as a string, one character at a time, into the equivalent integer until the string is exhausted.

In the registry of Windows 2000 and later versions, such an installed address string contains Unicode characters.

Note that NDIS does not validate the value at NetworkAddress. NDIS does not guarantee that this value is a valid address, that the value has the proper length, or even that the value is a network address. The caller of NdisReadNetworkAddress must therefore not make any assumptions about this value and must itself validate the value. If the caller determines that the value is out of bounds, it should not use the value; instead, it should use the permanent medium access control (MAC) address or a default address.

Requirements

Requirement	Value
Minimum supported client	Supported for NDIS 6.0 and later drivers in Windows Vista and later. Supported for NDIS 5.1 drivers (see NdisReadNetworkAddress (NDIS 5.1)) in Windows XP and later.
Target Platform	Universal
Header	ndis.h (include Ndis.h)
Library	Ndis.lib
IRQL	PASSIVE_LEVEL
DDI compliance rules	Irql_Miscellaneous_Function(ndis)