InternetOpen function
Initializes an application's use of the WinINet functions.
HINTERNET InternetOpen(
_In_ LPCTSTR lpszAgent,
_In_ DWORD
dwAccessType,
_In_ LPCTSTR lpszProxyName,
_In_ LPCTSTR lpszProxyBypass,
_In_ DWORD
Parameters
lpszAgent [in]
Pointer to a null-terminated string
that specifies the name of the application or entity calling the WinINet functions. This name is used as the user agent in the HTTP protocol.
dwAccessType [in]
Type of access required. This parameter can be one of the following values.
ValueMeaning
INTERNET_OPEN_TYPE_DIRECT
Resolves all host names locally.
INTERNET_OPEN_TYPE_PRECONFIG
Retrieves the proxy or direct configuration from the registry.
INTERNET_OPEN_TYPE_PRECONFIG_WITH_NO_AUTOPROXY
Retrieves the proxy or direct configuration from the registry and prevents the use of a startup Microsoft JScript or Internet Setup (INS) file.
INTERNET_OPEN_TYPE_PROXY
Passes requests to the proxy unless a proxy bypass list is supplied and the name to be resolved bypasses the proxy. In this case, the function uses
INTERNET_OPEN_TYPE_DIRECT.
lpszProxyName [in]
Pointer to a null-terminated string
that specifies the name of the proxy server(s) to use when proxy access is specified by setting
dwAccessType to
INTERNET_OPEN_TYPE_PROXY. Do not use an empty string, because
InternetOpen will use it as the proxy name. The WinINet functions recognize only CERN type proxies (HTTP only) and the TIS FTP gateway (FTP only). If Microsoft Internet Explorer is installed, these functions also support SOCKS proxies. FTP requests can be made through a CERN type proxy either by changing them to an HTTP request or by using
dwAccessType is not set to
INTERNET_OPEN_TYPE_PROXY, this parameter is ignored and should be NULL. For more information about listing proxy servers, see the
section of
lpszProxyBypass [in]
Pointer to a null-terminated string
that specifies an optional list of host names or IP addresses, or both, that should not be routed through the proxy when
dwAccessType is set to
INTERNET_OPEN_TYPE_PROXY. The list can contain wildcards. Do not use an empty string, because
InternetOpen will use it as the proxy bypass list. If this parameter specifies the "&local&" macro, the function bypasses the proxy for any host name that does not contain a period.
By default, WinINet will bypass the proxy for requests that use the host names "localhost", "loopback", "127.0.0.1", or "[::1]". This behavior exists because a remote proxy server typically will not resolve these addresses properly.Internet Explorer 9:
You can remove the local computer from the proxy bypass list using the "&-loopback&" macro.
dwAccessType is not set to
INTERNET_OPEN_TYPE_PROXY, this parameter is ignored and should be NULL.
dwFlags [in]
Options. This parameter can be a combination of the following values.
ValueMeaning
INTERNET_FLAG_ASYNC
Makes only asynchronous requests on handles descended from the handle returned from this function.
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.
INTERNET_FLAG_OFFLINE
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.
Return value
Returns a valid handle that the application passes to subsequent WinINet functions. If
InternetOpen fails, it returns NULL. To retrieve a specific error message, call
InternetOpen is the first WinINet function called by an application. It tells the Internet DLL to initialize internal data structures and prepare for future calls from the application. When the application finishes using the Internet functions, it should call
to free the handle and any associated resources.
The application can make any number of calls to
InternetOpen, though a single call is normally sufficient. The application might need to define separate behaviors for each
InternetOpen instance, such as different proxy servers configured for each.
After the calling application has finished using the
handle returned by
InternetOpen, it must be closed using the
Like all other aspects of the WinINet API, this function cannot be safely called from within DllMain or the constructors and destructors of global objects.
WinINet does not support server implementations. In addition, it should not be used from a service.
For server implementations or services use .
Requirements
Minimum supported client
Windows 2000 Professional [desktop apps only]
Minimum supported server
Windows 2000 Server [desktop apps only]
Wininet.lib
Wininet.dll
Unicode and ANSI names
InternetOpenW (Unicode) and InternetOpenA (ANSI)
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