API Flags
Many of the WinINet functions accept an array of flags as a parameter. The following is a brief description of the defined flags.
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INTERNET_COOKIE_EVALUATE_P3P
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0x80
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Indicates that a Platform for Privacy Protection (P3P) header is to be associated with a cookie.
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INTERNET_COOKIE_THIRD_PARTY
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0x10
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Indicates that a third-party cookie is being set or retrieved.
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INTERNET_FLAG_ASYNC
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0x10000000
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Makes only asynchronous requests on handles descended from the handle returned from this function. Only the InternetOpen function uses this flag.
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INTERNET_FLAG_CACHE_ASYNC
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0x00000080
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Allows a lazy cache write.
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INTERNET_FLAG_CACHE_IF_NET_FAIL
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0x00010000
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Returns the resource from the cache if the network request for the resource fails due to an ERROR_INTERNET_CONNECTION_RESET or ERROR_INTERNET_CANNOT_CONNECT error. This flag is used by HttpOpenRequest.
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INTERNET_FLAG_DONT_CACHE
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0x04000000
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Does not add the returned entity to the cache. This is identical to the preferred value, INTERNET_FLAG_NO_CACHE_WRITE.
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INTERNET_FLAG_EXISTING_CONNECT
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0x20000000
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Attempts to use an existing InternetConnect object if one exists with the same attributes required to make the request. This is useful only with FTP operations, since FTP is the only protocol that typically performs multiple operations during the same session. WinINet caches a single connection handle for each HINTERNET handle generated by InternetOpen. The InternetOpenUrl and InternetConnect functions use this flag for Http and Ftp connections.
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INTERNET_FLAG_FORMS_SUBMIT
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0x00000040
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Indicates that this is a Forms submission.
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INTERNET_FLAG_FROM_CACHE
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0x01000000
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Does not make network requests. All entities are returned from the cache. If the requested item is not in the cache, a suitable error, such as ERROR_FILE_NOT_FOUND, is returned. Only the InternetOpen function uses this flag.
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INTERNET_FLAG_FWD_BACK
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0x00000020
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Indicates that the function should use the copy of the resource that is currently in the Internet cache. The expiration date and other information about the resource is not checked. If the requested item is not found in the Internet cache, the system attempts to locate the resource on the network. This value was introduced in Microsoft Internet Explorer 5 and is associated with the Forward and Back button operations of Internet Explorer.
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INTERNET_FLAG_HYPERLINK
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0x00000400
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Forces a reload if there is no Expires time and no LastModified time returned from the server when determining whether to reload the item from the network. This flag can be used by FtpFindFirstFile, FtpGetFile, FtpOpenFile, FtpPutFile, HttpOpenRequest, and InternetOpenUrl.
Windows XP and Windows Server 2003 R2 and earlier: Also used by GopherFindFirstFile and GopherOpenFile.
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INTERNET_FLAG_IGNORE_CERT_CN_INVALID
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0x00001000
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Disables checking of SSL/PCT-based certificates that are returned from the server against the host name given in the request. WinINet uses a simple check against certificates by comparing for matching host names and simple wildcarding rules. This flag can be used by HttpOpenRequest and InternetOpenUrl (for HTTP requests).
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INTERNET_FLAG_IGNORE_CERT_DATE_INVALID
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0x00002000
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Disables checking of SSL/PCT-based certificates for proper validity dates. This flag can be used by HttpOpenRequest and InternetOpenUrl (for HTTP requests).
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INTERNET_FLAG_IGNORE_REDIRECT_TO_HTTP
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0x00008000
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Disables detection of this special type of redirect. When this flag is used, WinINet transparently allows redirects from HTTPS to HTTP URLs. This flag can be used by HttpOpenRequest and InternetOpenUrl (for HTTP requests).
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INTERNET_FLAG_IGNORE_REDIRECT_TO_HTTPS
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0x00004000
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Disables detection of this special type of redirect. When this flag is used, WinINet transparently allow redirects from HTTP to HTTPS URLs. This flag can be used by HttpOpenRequest and InternetOpenUrl (for HTTP requests).
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INTERNET_FLAG_KEEP_CONNECTION
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0x00400000
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Uses keep-alive semantics, if available, for the connection. This flag is used by HttpOpenRequest and InternetOpenUrl (for HTTP requests). This flag is required for Microsoft Network (MSN), NTLM, and other types of authentication.
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INTERNET_FLAG_MAKE_PERSISTENT
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0x02000000
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No longer supported.
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INTERNET_FLAG_MUST_CACHE_REQUEST
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0x00000010
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Identical to the preferred value, INTERNET_FLAG_NEED_FILE. Causes a temporary file to be created if the file cannot be cached. This flag can be used by FtpFindFirstFile, FtpGetFile, FtpOpenFile, FtpPutFile, HttpOpenRequest, and InternetOpenUrl.
Windows XP and Windows Server 2003 R2 and earlier: Also used by GopherFindFirstFile and GopherOpenFile.
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INTERNET_FLAG_NEED_FILE
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0x00000010
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Causes a temporary file to be created if the file cannot be cached. This flag can be used by FtpFindFirstFile, FtpGetFile, FtpOpenFile, FtpPutFile, HttpOpenRequest, and InternetOpenUrl.
Windows XP and Windows Server 2003 R2 and earlier: Also used by GopherFindFirstFile and GopherOpenFile.
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INTERNET_FLAG_NO_AUTH
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0x00040000
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Does not attempt authentication automatically. This flag can be used by HttpOpenRequest and InternetOpenUrl (for HTTP requests).
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INTERNET_FLAG_NO_AUTO_REDIRECT
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0x00200000
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Does not automatically handle redirection in HttpSendRequest. This flag can also be used by InternetOpenUrl for HTTP requests.
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INTERNET_FLAG_NO_CACHE_WRITE
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0x04000000
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Does not add the returned entity to the cache. This flag is used by , HttpOpenRequest, and InternetOpenUrl.
Windows XP and Windows Server 2003 R2 and earlier: Also used by GopherFindFirstFile and GopherOpenFile.
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INTERNET_FLAG_NO_COOKIES
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0x00080000
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Does not automatically add cookie headers to requests, and does not automatically add returned cookies to the cookie database. This flag can be used by HttpOpenRequest and InternetOpenUrl (for HTTP requests).
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INTERNET_FLAG_NO_UI
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0x00000200
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Disables the cookie dialog box. This flag can be used by HttpOpenRequest and InternetOpenUrl (HTTP requests only).
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INTERNET_FLAG_OFFLINE
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0x01000000
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Identical to INTERNET_FLAG_FROM_CACHE. Does not make network requests. All entities are returned from the cache. If the requested item is not in the cache, a suitable error, such as ERROR_FILE_NOT_FOUND, is returned. Only the InternetOpen function uses this flag.
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INTERNET_FLAG_PASSIVE
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0x08000000
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Uses passive FTP semantics. Only InternetConnect and InternetOpenUrl use this flag. InternetConnect uses this flag for FTP requests, and InternetOpenUrl uses this flag for FTP files and directories.
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INTERNET_FLAG_PRAGMA_NOCACHE
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0x00000100
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Forces the request to be resolved by the origin server, even if a cached copy exists on the proxy. The InternetOpenUrl function (on HTTP and HTTPS requests only) and HttpOpenRequest function use this flag.
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INTERNET_FLAG_RAW_DATA
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0x40000000
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Returns the data as a WIN32_FIND_DATA structure when retrieving FTP directory information. If this flag is not specified or if the call is made through a CERN proxy, InternetOpenUrl returns the HTML version of the directory. Only the InternetOpenUrl function uses this flag.
Windows XP and Windows Server 2003 R2 and earlier: Also returns a GOPHER_FIND_DATA structure when retrieving Gopher directory information.
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INTERNET_FLAG_READ_PREFETCH
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0x00100000
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This flag is currently disabled.
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INTERNET_FLAG_RELOAD
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0x80000000
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Forces a download of the requested file, object, or directory listing from the origin server, not from the cache. The FtpFindFirstFile, FtpGetFile, FtpOpenFile, FtpPutFile, HttpOpenRequest, and InternetOpenUrl functions use this flag.
Windows XP and Windows Server 2003 R2 and earlier: Also used by GopherFindFirstFile and GopherOpenFile.
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INTERNET_FLAG_RESTRICTED_ZONE
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0x00020000
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Indicates that the cookie being set is associated with an untrusted site.
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INTERNET_FLAG_RESYNCHRONIZE
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0x00000800
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Reloads HTTP resources if the resource has been modified since the last time it was downloaded. All FTP resources are reloaded. This flag can be used by FtpFindFirstFile, FtpGetFile, FtpOpenFile, FtpPutFile, HttpOpenRequest, and InternetOpenUrl.
Windows XP and Windows Server 2003 R2 and earlier: Also used by GopherFindFirstFile and GopherOpenFile, and Gopher resources are reloaded.
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INTERNET_FLAG_SECURE
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0x00800000
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Uses secure transaction semantics. This translates to using Secure Sockets Layer/Private Communications Technology (SSL/PCT) and is only meaningful in HTTP requests. This flag is used by HttpOpenRequest and InternetOpenUrl, but this is redundant if https:// appears in the URL.The InternetConnect function uses this flag for HTTP connections; all the request handles created under this connection will inherit this flag.
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INTERNET_FLAG_TRANSFER_ASCII
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0x00000001
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Transfers file as ASCII (FTP only). This flag can be used by FtpOpenFile, FtpGetFile, and FtpPutFile.
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INTERNET_FLAG_TRANSFER_BINARY
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0x00000002
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Transfers file as binary (FTP only). This flag can be used by FtpOpenFile, FtpGetFile, and FtpPutFile.
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INTERNET_NO_CALLBACK
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0x00000000
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Indicates that no callbacks should be made for that API. This is used for the dxContext parameter of the functions that allow asynchronous operations.
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INTERNET_OPTION_SUPPRESS_SERVER_AUTH
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104
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Sets an HTTP request object such that it will not logon to origin servers, but will perform automatic logon to HTTP proxy servers. This option differs from the Request flag INTERNET_FLAG_NO_AUTH, which prevents authentication to both proxy servers and origin servers. Setting this mode will suppress the use of any credential material (either previously provided username/password or client SSL certificate) when communicating with an origin server. However, if the request must transit via an authenticating proxy, WinINet will still perform automatic authentication to the HTTP proxy per the Intranet Zone settings for the user. The default Intranet Zone setting is to permit automatic logon using the user s default credentials. To ensure suppression of all identifying information, the caller should combine INTERNET_OPTION_SUPPRESS_SERVER_AUTH with the INTERNET_FLAG_NO_COOKIES request flag. This option may only be set on request objects before they have been sent. Attempts to set this option after the request has been sent will return ERROR_INTERNET_INCORRECT_HANDLE_STATE. No buffer is required for this option. This is used by InternetSetOption on handles returned by HttpOpenRequest only. Version: Requires Internet Explorer 8.0 or later.
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WININET_API_FLAG_ASYNC
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0x00000001
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Forces asynchronous operations.
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WININET_API_FLAG_SYNC
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0x00000004
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Forces synchronous operations.
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WININET_API_FLAG_USE_CONTEXT
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0x00000008
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Forces the API to use the context value, even if it is set to zero.
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Note
WinINet does not support server implementations. In addition, it should not be used from a service. For server implementations or services use Microsoft Windows HTTP Services (WinHTTP).
Requirement | Value |
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Minimum supported client |
Windows 2000 Professional [desktop apps only] |
Minimum supported server |
Windows 2000 Server [desktop apps only] |
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