Networking Developer Platform

Retrieves header information associated with an HTTP request.

Syntax

BOOL HttpQueryInfo(
  __in     HINTERNET hRequest,
  __in     DWORD dwInfoLevel,
  __inout  LPVOID lpvBuffer,
  __inout  LPDWORD lpdwBufferLength,
  __inout  LPDWORD lpdwIndex
);

Parameters

hRequest

Handle returned by HttpOpenRequest or InternetOpenUrl.

dwInfoLevel

Combination of an attribute to be retrieved and flags that modify the request. For a list of possible attribute and modifier values, see Query Info Flags.

lpvBuffer

Pointer to a buffer to receive the requested information. This parameter must not be NULL.

lpdwBufferLength

Pointer to a variable that contains, on entry, the size in bytes of the buffer pointed to by lpvBuffer.

When the function returns successfully, this variable contains the number of bytes of information written to the buffer. In the case of a string, the byte count does not include the string's terminating null character.

When the function fails with an extended error code of ERROR_INSUFFICIENT_BUFFER, the variable pointed to by lpdwBufferLength contains on exit the size, in bytes, of a buffer large enough to receive the requested information. The calling application can then allocate a buffer of this size or larger, and call the function again.

lpdwIndex

Pointer to 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 the following types of data from HttpQueryInfo:

• Strings (default)
• SYSTEMTIME (for dates)
• DWORD (for STATUS_CODE, CONTENT_LENGTH, and so on, if HTTP_QUERY_FLAG_NUMBER has been used)

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

HttpQueryInfo is available in Microsoft Internet Explorer 3.0 for the ANSI character set and in Internet Explorer 4.0 or later for ANSI and Unicode characters.

Example Code

This example demonstrates a call to HttpQueryInfo.

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

Requirements

See Also

HTTP Sessions
WinINet Functions
Retrieving HTTP Headers

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Build date: 2/28/2008