HttpQueryInfo Function

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Retrieves header information associated with an HTTP request.

Syntax

BOOL HttpQueryInfo(
    IN HINTERNET hRequest,
    IN DWORD dwInfoLevel,
    IN LPVOID lpvBuffer,
    IN LPDWORD lpdwBufferLength,
    IN OUT LPDWORD lpdwIndex,
);

The actual syntax of this function varies between its ANSI and Unicode implementations. For more information, see Win32 Internet Functions Syntax.

Parameters

hRequest

HINTERNET request handle returned by HttpOpenRequest or InternetOpenUrl.

dwInfoLevel

Unsigned long integer value that contains a combination of an attribute to retrieve and the flags that modify the request. The attribute can be any one of the Attributes, and the flag can be any one of the Modifiers on the Query Info Flags page.

lpvBuffer

Address of the buffer that receives the information.

lpdwBufferLength

Address of a value that contains the length of the data buffer, in TCHARs. When the function returns, this parameter contains the address of a value specifying the length of the information written to the buffer. When the function returns strings, the following rules apply:

• If the function succeeds, lpdwBufferLength specifies the length of the string, in TCHARs, minus 1 for the terminating null.
• If the function fails and ERROR_INSUFFICIENT_BUFFER is returned, lpdwBufferLength specifies the number of bytes that the application must allocate to receive the string.

lpdwIndex

Address of a zero-based header index used to enumerate multiple headers with the same name. When calling the function, this parameter is the index of the specified header to return. When the function returns, this parameter is the index of the next header. If the next index cannot be found, ERROR_HTTP_HEADER_NOT_FOUND is returned.

Return Value

Returns TRUE if successful, or FALSE otherwise. To get extended error information, call GetLastError.

Remarks

You can retrieve different types of data from HttpQueryInfo:

• Strings (default)
• SYSTEMTIME (for Data: Expires:, headers)
• DWORD (for STATUS_CODE, CONTENT_LENGTH, and so on, if HTTP_QUERY_FLAG_NUMBER has been used)

If your application needs the data returned as a data type other than a string, you must include the appropriate modifier with the attribute passed to dwInfoLevel.

Example

This example demonstrates a call to HttpQueryInfo.

bRet = HttpQueryInfo(hResource, HTTP_QUERY_RAW_HEADERS_CRLF,
                   lpvSomeBuffer, &dwSize, NULL));

Function Information

Windows NT	Use version 4.0. Implemented as ANSI and Unicode functions.
Windows	Use Windows 95 and later. Implemented as ANSI and Unicode functions.
Header	Wininet.h
Import library	Wininet.lib
Minimum availability	Internet Explorer 3.0 (ANSI only), 5 (ANSI and Unicode)

Windows CE

Windows CE	Use version 2.12 and later. Implemented as ANSI and Unicode functions.
Minimum availability	Internet Explorer 4.0

See Also

Microsoft Win32 Internet Functions Overview, HTTP Sessions, Microsoft Win32 Internet Functions Reference, Microsoft Win32 Internet Functions Tutorials, Retrieving HTTP Headers, HTTP Functions