The Windows Sockets WSALookupServiceNext function is called after obtaining a handle from a previous call to WSALookupServiceBegin in order to retrieve the requested service information.
The provider will pass back a WSAQUERYSET structure in the lpqsResults buffer. The client should continue to call this function until it returns WSA_E_NOMORE, indicating that all of WSAQUERYSET has been returned.
INT WSALookupServiceNext (
HANDLE hLookup,
DWORD dwControlFlags,
LPDWORD lpdwBufferLength,
LPWSAQUERYSET lpqsResults
);
The dwControlFlags specified in this function and the ones specified at the time of WSALookupServiceBegin are treated as "restrictions" for the purpose of combination. The restrictions are combined between the ones at WSALookupServiceBegin time and the ones at WSALookupServiceNext time. Therefore the flags at WSALookupServiceNext can never increase the amount of data returned beyond what was requested at WSALookupServiceBegin, although it is NOT an error to specify more or fewer flags. The flags specified at a given WSALookupServiceNext apply only to that call.
The dwControlFlags LUP_FLUSHPREVIOUS and LUP_RES_SERVICE are exceptions to the "combined restrictions" rule (because they are "behavior" flags instead of "restriction" flags). If either of these flags are used in WSALookupServiceNext they have their defined effect regardless of the setting of the same flags at WSALookupServiceBegin.
For example, if LUP_RETURN_VERSION is specified at WSALookupServiceBegin the service provider retrieves records including the "version". If LUP_RETURN_VERSION is NOT specified at WSALookupServiceNext, the returned information does not include the "version", even though it was available. No error is generated.
Also for example, if LUP_RETURN_BLOB is NOT specified at WSALookupServiceBegin but is specified at WSALookupServiceNext, the returned information does not include the private data. No error is generated.
The following table describes how the query results are represented in the WSAQUERYSET structure.
| WSAQUERYSET Field Name | Result Interpretation |
|---|---|
| dwSize | Will be set to sizeof(WSAQUERYSET). This is used as a versioning mechanism. |
| DwOuputFlags | RESULT_IS_ALIAS flag indicates this is an alias result. |
| LpszServiceInstanceName | Referenced string contains service name. |
| LpServiceClassId | The GUID corresponding to the service class. |
| LpVersion | References version number of the particular service instance. |
| LpszComment | Optional comment string supplied by service instance. |
| DwNameSpace | Name space in which the service instance was found. |
| LpNSProviderId | Identifies the specific name space provider that supplied this query result. |
| LpszContext | Specifies the context point in a hierarchical name space at which the service is located. |
| DwNumberOfProtocols | Undefined for results. |
| LpafpProtocols | Undefined for results, all needed protocol information is in the CSADDR_INFO structures. |
| LpszQueryString | When dwControlFlags includes LUP_RETURN_QUERY_STRING, this field returns the unparsed remainder of the lpszServiceInstanceName specified in the original query. For example, in a name space that identifies services by hierarchical names that specify a host name and a file path within that host, the address returned might be the host address and the unparsed remainder might be the file path. If the lpszServiceInstanceName is fully parsed and LUP_RETURN_QUERY_STRING is used, this field is NULL or points to a zero-length string. |
| DwNumberOfCsAddrs | Indicates the number of elements in the array of CSADDR_INFO structures. |
| LpcsaBuffer | A pointer to an array of CSADDR_INFO structures, with one complete transport address contained within each element. |
| LpBlob | (Optional) This is a pointer to a provider-specific entity. |
The return value is zero if the operation was successful. Otherwise, the value SOCKET_ERROR is returned, and a specific error number can be retrieved by calling WSAGetLastError.
| WSA_E_NO_MORE | There is no more data available. In Windows Sockets version 2, conflicting error codes are defined for WSAENOMORE (10102) and WSA_E_NO_MORE (10110). The error code WSAENOMORE will be removed in a future version and only WSA_E_NO_MORE will remain. For Windows Sockets version 2, however, applications should check for both WSAENOMORE and WSA_E_NO_MORE for the widest possible compatibility with Name Space Providers that use either one. |
| WSA_E_CANCELLED | A call to WSALookupServiceEnd was made while this call was still processing. The call has been canceled. The data in the lpqsResults buffer is undefined. In Windows Sockets version 2, conflicting error codes are defined for WSAECANCELLED (10103) and WSA_E_CANCELLED (10111). The error code WSAECANCELLED will be removed in a future version and only WSA_E_CANCELLED will remain. For Windows Sockets version 2, however, applications should check for both WSAECANCELLED and WSA_E_CANCELLED for the widest possible compatibility with Name Space Providers that use either one. |
| WSAEFAULT | The lpqsResults buffer was too small to contain a WSAQUERYSET set. |
| WSAEINVAL | One or more required parameters were invalid or missing. |
| WSA_INVALID_HANDLE | The specified Lookup handle is invalid. |
| WSANOTINITIALIZED | The WS2_32.DLL has not been initialized. The application must first call WSAStartup before calling any Windows Sockets functions. |
| WSANO_DATA | The name was ound in the database, but no data matching the given restrictions was located. |
| WSASERVICE_NOT_FOUND | No such service is known. The service cannot be found in the specified name space. |
| WSA NOT ENOUGH MEMORY | There was insufficient memory to perform the operation. |
Windows NT: Yes
Windows: Yes
Windows CE: Unsupported.
Header: Declared in winsock2.h.
Import Library: Link with ws2_32.lib.
WSALookupServiceBegin, WSALookupServiceEnd