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4/8/2010

This function queries for information about an HTTP request.

Syntax 

BOOL WINAPI HttpQueryInfo(
  HINTERNET 
hRequest, 
  DWORD 
dwInfoLevel, 
  LPVOID 
lpBuffer, 
  LPDWORD 
lpdwBufferLength, 
  LPDWORD 
lpdwIndex
);

Parameters

hRequest

[in] Open HTTP request handle returned by HttpOpenRequestor InternetOpen.

dwInfoLevel

[in] Specifies a combination of the attribute to query and the flags that modify the request. The following table shows the possible attribute values.

Value Description

HTTP_QUERY_ACCEPT

Retrieves the acceptable media types for the response.

HTTP_QUERY_ACCEPT_CHARSET

Retrieves the acceptable character sets for the response.

HTTP_QUERY_ACCEPT_ENCODING

Retrieves the acceptable content-coding values for the response.

HTTP_QUERY_ACCEPT_LANGUAGE

Retrieves the acceptable natural languages for the response.

HTTP_QUERY_ACCEPT_RANGES

Retrieves the types of range requests that are accepted for a resource.

HTTP_QUERY_AGE

Retrieves the Age response-header field, which contains the sender's estimate of the amount of time since the response was generated at the origin server.

HTTP_QUERY_ALLOW

Receives the methods supported by the server.

HTTP_QUERY_AUTHORIZATION

Retrieves the authorization credentials used for a request.

HTTP_QUERY_CACHE_CONTROL

Retrieves the cache control directives.

HTTP_QUERY_CONNECTION

Retrieves any options that are specified for a particular connection and must not be communicated by proxies over further connections.

HTTP_QUERY_COOKIE

Retrieves any cookies associated with the request.

HTTP_QUERY_CONTENT_BASE

Retrieves the base URI for resolving relative URLs within the entity.

HTTP_QUERY_CONTENT_DESCRIPTION

Obsolete. Maintained for legacy application compatibility only.

HTTP_QUERY_CONTENT_DISPOSITION

Obsolete. Maintained for legacy application compatibility only.

HTTP_QUERY_CONTENT_ENCODING

Receives any additional content codings that have been applied to the entire resource.

HTTP_QUERY_CONTENT_ID

Receives the content identification.

HTTP_QUERY_CONTENT_LANGUAGE

Receives the language that the content is in.

HTTP_QUERY_CONTENT_LENGTH

Receives the size of the resource, in bytes.

HTTP_QUERY_CONTENT_LOCATION

Retrieves the resource location for the entity enclosed in the message.

HTTP_QUERY_CONTENT_MD5

Retrieves a MD5 digest of the entity-body for the purpose of providing an end-to-end message integrity check (MIC) for the entity-body.

HTTP_QUERY_CONTENT_RANGE

Retrieves the location in the full entity-body where the partial entity-body should be inserted and the total size of the full entity-body.

HTTP_QUERY_CONTENT_TRANSFER_ENCODING

Receives the additional content coding that has been applied to the resource.

HTTP_QUERY_CONTENT_TYPE

Receives the content type of the resource (such as text/html).

HTTP_QUERY_COST

No longer implemented.

HTTP_QUERY_DATE

Receives the date and time at which the message was originated.

HTTP_QUERY_DERIVED_FROM

No longer supported.

HTTP_QUERY_ETAG

Retrieves the entity tag for the associated entity.

HTTP_QUERY_EXPIRES

Receives the date and time after which the resource should be considered outdated.

HTTP_QUERY_FORWARDED

Obsolete. Maintained for legacy application compatibility only.

HTTP_QUERY_FROM

Retrieves the e-mail address for the human user who controls the requesting user agent if the From header is given.

HTTP_QUERY_HOST

Retrieves the Internet host and port number of the resource being requested.

HTTP_QUERY_IF_MATCH

Retrieves the contents of the If-Match request-header field.

HTTP_QUERY_IF_MODIFIED_SINCE

Retrieves the contents of the If-Modified-Since header.

HTTP_QUERY_IF_NONE_MATCH

Retrieves the contents of the If-None-Match request-header field.

HTTP_QUERY_IF_RANGE

Retrieves the contents of the If-Range request-header field. This header allows the client application to check if the entity related to a partial copy of the entity in the client application's cache has not been updated. If the entity has not been updated, send the parts that the client application is missing. If the entity has been updated, send the entire updated entity.

HTTP_QUERY_IF_UNMODIFIED_SINCE

Retrieves the contents of the If-Unmodified-Since request-header field.

HTTP_QUERY_LINK

Obsolete. Maintained for legacy application compatibility only.

HTTP_QUERY_LAST_MODIFIED

Receives the date and time at which the server believes the resource was last modified.

HTTP_QUERY_LOCATION

Retrieves the absolute URI used in a Location response-header.

HTTP_QUERY_MAX

Retrieves the maximum value of an HTTP_QUERY_* value.

HTTP_QUERY_MAX_FORWARDS

Retrieves the number of proxies or gateways that can forward the request to the next inbound server.

HTTP_QUERY_MESSAGE_ID

No longer implemented.

HTTP_QUERY_MIME_VERSION

Receives the version of the MIME protocol that was used to construct the message.

HTTP_QUERY_ORIG_URI

Obsolete. Maintained for legacy application compatibility only.

HTTP_QUERY_PRAGMA

Receives the implementation-specific directives that may apply to any recipient along the request/response chain.

HTTP_QUERY_PROXY_AUTHENTICATE

Retrieves the authentication scheme and realm returned by the proxy.

HTTP_QUERY_PROXY_AUTHORIZATION

Retrieves the header that is used to identify the user to a proxy that requires authentication.

HTTP_QUERY_PUBLIC

Receives methods available at this server.

HTTP_QUERY_RANGE

Retrieves the byte range of an entity.

HTTP_QUERY_RAW_HEADERS

Receives all the headers returned by the server. Each header is terminated by "\0". An additional "\0" terminates the list of headers.

HTTP_QUERY_RAW_HEADERS_CRLF

Receives all the headers returned by the server. Each header is separated by a carriage return/line feed (CR/LF) sequence.

HTTP_QUERY_REFERER

Receives the URI of the resource where the requested URI was obtained.

HTTP_QUERY_REFRESH

Obsolete. Maintained for legacy application compatibility only.

HTTP_QUERY_REQUEST_METHOD

Receives the verb that is being used in the request, typically GET or POST.

HTTP_QUERY_RETRY_AFTER

Retrieves the amount of time the service is expected to be unavailable.

HTTP_QUERY_SERVER

Retrieves information about the software used by the origin server to handle the request.

HTTP_QUERY_SET_COOKIE

Receives the value of the cookie set for the request.

HTTP_QUERY_STATUS_CODE

Receives the status code returned by the server.

HTTP_QUERY_STATUS_TEXT

Receives any additional text returned by the server on the response line.

HTTP_QUERY_TITLE

Obsolete. Maintained for legacy application compatibility only.

HTTP_QUERY_TRANSFER_ENCODING

Retrieves the type of transformation that has been applied to the message body so it can be correctly transferred between the sender and recipient.

HTTP_QUERY_UPGRADE

Retrieves the additional communication protocols that are supported by the server.

HTTP_QUERY_URI

Receives some or all of the Uniform Resource Identifiers (URIs) by which the Request-URI resource can be identified.

HTTP_QUERY_USER_AGENT

Retrieves information about the user agent that made the request.

HTTP_QUERY_VARY

Retrieves the header that indicates that the entity was selected from a number of available representations of the response using server-driven negotiation.

HTTP_QUERY_VERSION

Receives the last response code returned by the server.

HTTP_QUERY_VIA

Retrieves the intermediate protocols and recipients between the user agent and the server on requests, and between the origin server and the client on responses.

HTTP_QUERY_WARNING

Retrieves additional information about the status of a response that may not be reflected by the response status code.

HTTP_QUERY_WWW_AUTHENTICATE

Retrieves the authentication scheme and realm returned by the server.

The following table shows modifiers that can be used with the information values.

Value Description

HTTP_QUERY_CUSTOM

Causes HttpQueryInfoto search for the header name specified in lpvBufferand store the header information in lpvBuffer.

HTTP_QUERY_FLAG_COALESCE

Not supported.

HTTP_QUERY_FLAG_NUMBER

Returns the data as a 32-bit number for headers whose value is a number, such as the status code.

HTTP_QUERY_FLAG_REQUEST_HEADERS

Queries request headers only.

HTTP_QUERY_FLAG_SYSTEMTIME

Returns the header value as a standard Win32 SYSTEMTIMEstructure, which does not require the application to parse the data. Use for headers whose value is a date/time string, such as "Last-Modified-Time".
lpBuffer

[in, out] Long void pointer to the buffer that receives the information.

lpdwBufferLength

[in, out] Long pointer to a value that contains the length of the data buffer. When the function returns, this parameter contains the address of a value specifying the length of the information written to the buffer. The following list shows the rules that apply when the function returns strings:

  • If the function succeeds, lpdwBufferLengthspecifies the length of the string, in characters, minus 1 for the terminating null.

  • If the function fails and ERROR_INSUFFICIENT_BUFFER is returned, lpdwBufferLengthspecifies the number of bytes that the application must allocate to receive the string.

lpdwIndex

[in, out] Long 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

TRUE indicates success. FALSE indicates failure. To get extended error information, call GetLastError.

Remarks

HttpQueryInfois used to return response or request headers from an HTTP request.

The following list shows the types of data you can retrieve from HttpQueryInfo:

  • strings (default)

  • SYSTEMTIME (for Data: Expires:, headers)

  • DWORD (for STATUS_CODE, CONTENT_LENGTH, and so on if HTTP_QUERY_INFO_NUMBER has been used)

Requirements

Header wininet.h
Library wininet.lib
Windows Embedded CE Windows CE 2.0 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also