Query Info Flags (Winhttp.h)

These attributes and modifiers are used by WinHttpQueryHeaders.

The attribute flags are used by WinHttpQueryHeaders to indicate what information to retrieve. Most of the attribute flags map directly to a specific HTTP header. There are also some special flags, such as WINHTTP_QUERY_RAW_HEADERS, that are not related to a specific header.

WINHTTP_QUERY_ACCEPT

Retrieves the acceptable media types for the response.

WINHTTP_QUERY_ACCEPT_CHARSET

Retrieves the acceptable character sets for the response.

WINHTTP_QUERY_ACCEPT_ENCODING

Retrieves the acceptable content-coding values for the response.

WINHTTP_QUERY_ACCEPT_LANGUAGE

Retrieves the acceptable natural languages for the response.

WINHTTP_QUERY_ACCEPT_RANGES

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

WINHTTP_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 originating server.

WINHTTP_QUERY_ALLOW

Receives the HTTP verbs supported by the server.

WINHTTP_QUERY_AUTHENTICATION_INFO

Retrieves the Authentication-Info header.

WINHTTP_QUERY_AUTHORIZATION

Retrieves the authorization credentials used for a request.

WINHTTP_QUERY_CACHE_CONTROL

Retrieves the cache control directives.

WINHTTP_QUERY_CONNECTION

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

WINHTTP_QUERY_CONTENT_BASE

Retrieves the base Uniform Resource Identifier (URI) to resolve relative URLs within the entity.

WINHTTP_QUERY_CONTENT_DESCRIPTION

Obsolete. Maintained for legacy application compatibility.

WINHTTP_QUERY_CONTENT_DISPOSITION

Obsolete. Maintained for legacy application compatibility.

WINHTTP_QUERY_CONTENT_ENCODING

Retrieves additional content coding that has been applied to the entire resource.

WINHTTP_QUERY_CONTENT_ID

Retrieves the content identification.

WINHTTP_QUERY_CONTENT_LANGUAGE

Retrieves the language that the content is written in.

WINHTTP_QUERY_CONTENT_LENGTH

Retrieves the size of the resource, in bytes.

WINHTTP_QUERY_CONTENT_LOCATION

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

WINHTTP_QUERY_CONTENT_MD5

Retrieves an MD5 digest of the entity body for the purpose of providing an end-to-end message integrity check for the entity body. For more information, see RFC 1864.

WINHTTP_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.

WINHTTP_QUERY_CONTENT_TRANSFER_ENCODING

Retrieves an encoding transformation applicable to an entity-body. It may already have been applied, may need to be applied, or may be optionally applicable.

WINHTTP_QUERY_CONTENT_TYPE

Receives the content type of the resource, such as text or html.

WINHTTP_QUERY_COOKIE

Retrieves any cookies associated with the request.

WINHTTP_QUERY_COST

Not supported.

WINHTTP_QUERY_CUSTOM

Causes WinHttpQueryHeaders to search for the header name specified in the pwszName parameter and store the header information in lpBuffer. An application can use WINHTTP_OPTION_RECEIVE_RESPONSE_TIMEOUT to limit the maximum time this query waits for all headers to be received.

WINHTTP_QUERY_DATE

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

WINHTTP_QUERY_DERIVED_FROM

Not supported.

WINHTTP_QUERY_ETAG

Retrieves the entity tag for the associated entity.

WINHTTP_QUERY_EXPECT

Retrieves the Expect header, which indicates whether the client application should expect 100 series responses.

WINHTTP_QUERY_EXPIRES

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

WINHTTP_QUERY_FORWARDED

Obsolete. Maintained for legacy application compatibility.

WINHTTP_QUERY_FROM

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

WINHTTP_QUERY_HOST

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

WINHTTP_QUERY_IF_MATCH

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

WINHTTP_QUERY_IF_MODIFIED_SINCE

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

WINHTTP_QUERY_IF_NONE_MATCH

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

WINHTTP_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.

WINHTTP_QUERY_IF_UNMODIFIED_SINCE

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

WINHTTP_QUERY_LINK

Obsolete. Maintained for legacy application compatibility.

WINHTTP_QUERY_LAST_MODIFIED

Receives the date and time at which the resource was last modified. The date and time are determined by the server.

WINHTTP_QUERY_LOCATION

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

WINHTTP_QUERY_MAX

Indicates the maximum value of a WINHTTP_QUERY_* value. Not a query flag.

WINHTTP_QUERY_MAX_FORWARDS

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

WINHTTP_QUERY_MESSAGE_ID

Not supported.

WINHTTP_QUERY_MIME_VERSION

Receives the version of the Multipurpose Internet Mail Extensions (MIME) protocol that was used to construct the message.

WINHTTP_QUERY_ORIG_URI

Obsolete. Maintained for legacy application compatibility.

WINHTTP_QUERY_PRAGMA

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

WINHTTP_QUERY_PROXY_AUTHENTICATE

Retrieves the authentication scheme and realm returned by the proxy.

WINHTTP_QUERY_PROXY_AUTHORIZATION

Retrieves the header that is used to identify the user to a proxy that requires authentication. This header can only be retrieved before the request is sent to the server.

WINHTTP_QUERY_PROXY_CONNECTION

Retrieves the Proxy-Connection header.

WINHTTP_QUERY_PROXY_SUPPORT

Retrieves the Proxy-Support header.

WINHTTP_QUERY_PUBLIC

Receives HTTP verbs available at this server.

WINHTTP_QUERY_RANGE

Retrieves the byte range of an entity.

WINHTTP_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.

WINHTTP_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.

WINHTTP_QUERY_REFERER

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

WINHTTP_QUERY_REFRESH

Obsolete. Maintained for legacy application compatibility.

WINHTTP_QUERY_REQUEST_METHOD

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

WINHTTP_QUERY_RETRY_AFTER

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

WINHTTP_QUERY_SERVER

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

WINHTTP_QUERY_SET_COOKIE

Receives the value of the cookie set for the request.

WINHTTP_QUERY_STATUS_CODE

Receives the status code returned by the server. For a list of possible values, see HTTP Status Codes.

WINHTTP_QUERY_STATUS_TEXT

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

WINHTTP_QUERY_TITLE

Obsolete. Maintained for legacy application compatibility.

WINHTTP_QUERY_TRANSFER_ENCODING

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

WINHTTP_QUERY_UNLESS_MODIFIED_SINCE

Retrieves the Unless-Modified-Since header.

WINHTTP_QUERY_UPGRADE

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

WINHTTP_QUERY_URI

Receives some or all of the URI by which the Request-URI resource can be identified.

WINHTTP_QUERY_USER_AGENT

Retrieves information about the user agent that made the request.

WINHTTP_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.

WINHTTP_QUERY_VERSION

Retrieves the HTTP version that is present in the status line.

WINHTTP_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.

WINHTTP_QUERY_WARNING

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

WINHTTP_QUERY_WWW_AUTHENTICATE

Retrieves the authentication scheme and realm returned by the server.

The modifier flags are used in conjunction with an attribute flag to modify the request. Modifier flags either modify the format of the data returned or indicate where the WinHttpQueryHeaders function should search for the information.

WINHTTP_QUERY_FLAG_NUMBER

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

WINHTTP_QUERY_FLAG_REQUEST_HEADERS

Queries request headers only.

WINHTTP_QUERY_FLAG_SYSTEMTIME

Returns the header value as a SYSTEMTIME structure, 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".

WINHTTP_QUERY_FLAG_TRAILERS

Introduced in Windows 11, version 21H2 (10.0; Build 22000). Queries response trailers. Prior to querying response trailers, you must call WinHttpReadData until it returns 0 bytes read.

WINHTTP_QUERY_FLAG_WIRE_ENCODING

Introduced in Windows 11, version 21H2 (10.0; Build 22000). By default, WinHttpQueryHeaders performs a Unicode conversion before returning the header that was queried. If this flag is set, WinHttp returns the header to the caller without performing this conversion.

Requirements

Requirement	Value
Minimum supported client	Windows XP, Windows 2000 Professional with SP3 [desktop apps only]
Minimum supported server	Windows Server 2003, Windows 2000 Server with SP3 [desktop apps only]
Header	Winhttp.h

See also

• WinHTTP Versions