GetHostNameW function (winsock2.h)

Article
10/13/2021

The GetHostNameW function retrieves the standard host name for the local computer as a Unicode string.

Syntax

int WSAAPI GetHostNameW(
  [out] PWSTR name,
  [in]  int   namelen
);

Parameters

[out] name

A pointer to a buffer that receives the local host name as a null-terminated Unicode string.

[in] namelen

The length, in wide characters, of the buffer pointed to by the name parameter.

Return value

If no error occurs, GetHostNameW returns zero. Otherwise, it returns SOCKET_ERROR and a specific error code can be retrieved by calling WSAGetLastError.

Error code	Meaning
WSAEFAULT	The name parameter is a NULL pointer or is not a valid part of the user address space. This error is also returned if the buffer size specified by namelen parameter is too small to hold the complete host name.
WSANOTINITIALISED	A successful WSAStartup call must occur before using this function.
WSAENETDOWN	The network subsystem has failed.

Remarks

The GetHostNameW function returns the name of the local host into the buffer specified by the name parameter in Unicode (UTF-16). The host name is returned as a null-terminated Unicode string. The form of the host name is dependent on the Windows Sockets provider—it can be a simple host name, or it can be a fully qualified domain name. However, it is guaranteed that the name returned will be successfully parsed by GetAddrInfoW.

With the growth of the Internet, there is a growing need to identify Internet host names for other languages not represented by the ASCII character set. Identifiers which facilitate this need and allow non-ASCII characters (Unicode) to be represented as special ASCII character strings (Punycode) are known as Internationalized Domain Names (IDNs). A mechanism called Internationalizing Domain Names in Applications (IDNA) is used to handle IDNs in a standard fashion. The GetHostNameW function does not convert the local hostname between Punycode and Unicode. The GetAddrInfoW function provides support for Internationalized Domain Name (IDN) parsing and performs Punycode/IDN encoding and conversion.

If the GetHostNameW function is used on a cluster resource on Windows Server 2012 and the CLUSTER_NETWORK_NAME environment variable is defined, then the value in this environment variable overrides the actual hostname and is returned. On a cluster resource, the CLUSTER_NETWORK_NAME environment variable contains the name of the cluster.

The GetHostNameW function queries namespace providers to determine the local host name using the SVCID_HOSTNAME GUID defined in the Svgguid.h header file. If no namespace provider responds, then the GetHostNameW function returns the NetBIOS name of the local computer in Unicode.

The maximum length, in wide characters, of the string returned in the buffer pointed to by the name parameter is dependent on the namespace provider, but this string must be 256 wide characters or less. So if a buffer of 256 wide characters is passed in the name parameter and the namelen parameter is set to 256, the buffer size will always be adequate.

Note If no local host name has been configured, GetHostNameW must succeed and return a token host name that GetAddrInfoW can resolve.

Windows Phone 8: This function is supported for Windows Phone Store apps on Windows Phone 8 and later.

Windows 8.1 and Windows Server 2012 R2: This function is supported for Windows Store apps on Windows 8.1, Windows Server 2012 R2, and later.

Requirements

Requirement	Value
Minimum supported client	Windows 8.1, Windows 8 [desktop apps \| UWP apps]
Minimum supported server	Windows Server 2012 [desktop apps \| UWP apps]
Target Platform	Windows
Header	winsock2.h
Library	Ws2_32.lib
DLL	Ws2_32.dll