GetService
Important The
GetService function is a Microsoft-specific extension to the Windows Sockets 1.1
specification. This function is obsolete. For the convenience of Windows Sockets 1.1
developers, the reference material is below..
In Windows Sockets 2, this functionality is realized with the functions
detailed in
Protocol-Independent Name Resolution.
The
GetService function obtains information about a network service in the context of a set
of default name spaces or a specified name space. The network service is
specified by its type and name. The information about the service is obtained as a
set of
NS_SERVICE_INFO data structures.
INT GetService(
DWORD dwNameSpace,
| // specifies name space or spaces to search
|
PGUID lpGuid,
| // points to a GUID service type
|
LPTSTR lpServiceName,
| // points to a service name
|
DWORD dwProperties,
| // specifies service information to be obtained
|
LPVOID lpBuffer,
| // points to buffer to receive service information
|
LPDWORD lpdwBufferSize,
| // points to size of buffer, size of service information
|
LPSERVICE_ASYNC_INFO lpServiceAsyncInfo
| // reserved for future use, must be NULL
|
);
|
|
Parameters
dwNameSpace
Specifies the name space, or a set of default name spaces, that the operating
system will query for information about the specified network service.
Use one of the following constants to specify a name space:
Value
| Name Space
|
NS_DEFAULT
| A set of default name spaces. The operating system will query each name space
within this set. The set of default name spaces typically includes all the name
spaces installed on the system. System administrators, however, can exclude
particular name spaces from the set. NS_DEFAULT is the value that most
applications should use for dwNameSpace.
|
NS_DNS
| The Domain Name System used in the Internet for host name resolution.
|
NS_NETBT
| The NetBIOS over TCP/IP layer. All Windows NT systems register their computer
names with NetBIOS. This name space is used to resolve a computer name into an
IP address using this registration. Note that NS_NETBT may access a WINS server
to perform the resolution.
|
NS_SAP
| The Netware Service Advertising Protocol. This may access the Netware bindery
if appropriate. NS_SAP is a dynamic name space that allows registration of
services.
|
NS_TCPIP_HOSTS
| Looks up host names and IP addresses in the
<systemroot>\system32\drivers\etc\hosts file.
|
NS_TCPIP_LOCAL
| Local TCP/IP name resolution mechanisms, including comparisons against the
local host name and looks up host names and IP addresses in cache of host to IP
address mappings.
|
Most calls to
GetService should use the special value NS_DEFAULT. This lets a client get by with no
knowledge of which name spaces are available on an internetwork. The system
administrator determines name space access. Name spaces can come and go without the
client having to be aware of the changes.
lpGuid
Points to a globally unique identifier (
GUID) that specifies the type of the network service. The header file SVCGUID.H
includes
GUID service types from many well-known services within the DNS and SAP name
spaces.
lpServiceName
Points to a zero-terminated string that uniquely represents the service name.
For example, "MY SNA SERVER".
dwProperties
A set of bit flags that specify the service information that the function
obtains. Each of these bit flag constants, other than PROP_ALL, corresponds to a
particular member of the
SERVICE_INFO data structure. If the flag is set, the function puts information into the
corresponding member of the data structures stored in *
lpBuffer. The following bit flags are defined:
Value
| Name Space
|
PROP_COMMENT
| If this flag is set, the function stores data in the lpComment member of the data structures stored in *lpBuffer.
|
PROP_LOCALE
| If this flag is set, the function stores data in the lpLocale member of the data structures stored in *lpBuffer.
|
PROP_DISPLAY_HINT
| If this flag is set, the function stores data in the dwDisplayHint member of the data structures stored in *lpBuffer.
|
PROP_VERSION
| If this flag is set, the function stores data in the dwVersion member of the data structures stored in *lpBuffer.
|
PROP_START_TIME
| If this flag is set, the function stores data in the dwTime member of the data structures stored in *lpBuffer.
|
PROP_MACHINE
| If this flag is set, the function stores data in the lpMachineName member of the data structures stored in *lpBuffer.
|
PROP_ADDRESSES
| If this flag is set, the function stores data in the lpServiceAddress member of the data structures stored in *lpBuffer.
|
PROP_SD
| If this flag is set, the function stores data in the ServiceSpecificInfo member of the data structures stored in *lpBuffer.
|
PROP_ALL
| If this flag is set, the function stores data in all of the members of the
data structures stored in *lpBuffer.
|
lpBuffer
Points to a buffer to receive an array of
NS_SERVICE_INFO structures and associated service information. Each
NS_SERVICE_INFO structure contains service information in the context of a particular name
space. Note that if
dwNameSpace is NS_DEFAULT, the function stores more than one structure into the buffer;
otherwise, just one structure is stored.
Each
NS_SERVICE_INFO structure contains a
SERVICE_INFO structure. The members of these
SERVICE_INFO structures will contain valid data based on the bit flags that are set in the
dwProperties parameter. If a member's corresponding bit flag is not set in
dwProperties, the member's value is undefined.
The function stores the
NS_SERVICE_INFO structures in a consecutive array, starting at the beginning of the buffer.
The pointers in the contained
SERVICE_INFO structures point to information that is stored in the buffer between the end
of the
NS_SERVICE_INFO structures and the end of the buffer.
lpdwBufferSize
Points to a variable that, on input, contains the size, in bytes, of the
buffer pointed to by
lpBuffer. On output, this variable contains the number of bytes required to store the
requested information. If this output value is greater than the input value,
the function has failed due to insufficient buffer size.
lpServiceAsyncInfo
This parameter is reserved for future use. It must be set to NULL.
Return Values
If the function succeeds, the return value is the number of
NS_SERVICE_INFO structures stored in *
lpBuffer. Zero indicates that no structures were stored.
If the function fails, the return value is SOCKET_ERROR (
1). To get extended error information, call
GetLastError.
GetLastError may return one of the following extended error values:
Value
| Meaning
|
ERROR_INSUFFICIENT_BUFFER
| The buffer pointed to by lpBuffer is too small to receive all of the requested information. Call the function
with a buffer at least as large as the value returned in *lpdwBufferSize.
|
ERROR_SERVICE_NOT_FOUND
| The specified service was not found, or the specified name space is not in
use. The function return value is zero in this case.
|
See Also
SetService,
NS_SERVICE_INFO,
SERVICE_INFO
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