HttpQueryInfoHttpQueryInfo*
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HttpQueryInfo

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

Queries for information about an HTTP request.

hHttpRequest
Open HTTP request handle returned by HttpOpenRequest or InternetOpenUrl.
dwInfoLevel
Combination of the attribute to query and the flags that modify the request. The attributes can be any of the following values:
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. For more information, see RFC1864, The Content-MD5 Header Field, at http://ds.internic.net/rfc/rfc1864.txtExternal Link for more information.
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. For a list of possible values, see HTTP Status Codes.
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 safely 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 modifiers can be used with the information values:

HTTP_QUERY_CUSTOM
Causes HttpQueryInfo to search for the header name specified in lpvBuffer and store the header information in lpvBuffer.
HTTP_QUERY_FLAG_COALESCE
Combines the values from headers with the same name into the output buffer.
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 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".
lpvBuffer
Address of the buffer that receives the information.
lpdwBufferLength
Address of 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. When the function returns strings, the following rules apply:
  • If the function succeeds, lpdwBufferLength specifies the length of the string, in characters, 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.

HttpQueryInfo is used to return response or request headers from an HTTP request.

You can retrieve different types of data from HttpQueryInfo:

See also HttpOpenRequest

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