This function begins reading a complete FTP or HTTP Universal Resource Locator (URL). For a relative URL and a base URL separated by blank spaces, InternetCanonicalizeUrl must be invoked first.
At a Glance
| Header file: | Wininet.h |
| Windows CE versions: | 2.0 and later |
Syntax
HINTERNET InternetOpenUrl( HINTERNET hInternetSession,
LPCTSTR lpszUrl, LPCTSTR lpszHeaders , DWORD dwHeadersLength, DWORD dwFlags, DWORD dwContext);
Parameters
hInternetSession
Handle to the current Internet session. The handle must have been returned by a previous call to InternetOpen.
lpszUrl
Long pointer to a null-terminated string that contains the URL to begin reading. Only URLs beginning with ftp:, http:, or https: are supported.
lpszHeaders
Long pointer to a null-terminated string that contains the headers to be sent to the HTTP server. (For more information, see the description of the lpszHeaders parameter in the HttpSendRequest function.)
dwHeadersLength
Specifies the length, in characters, of the additional headers. If this parameter is -1L and lpszHeaders is not NULL, lpszHeaders is assumed to be zero-terminated (ASCIIZ) and the length is calculated.
dwFlags
Specifies a bitmask of action flags. It is one of the following values:
| Value | Description |
| INTERNET_FLAG_DONT_CACHE | Does not cache the data, either locally or in any gateways. Identical to the preferred value INTERNET_FLAG_NO_CACHE_WRITE. |
| INTERNET_FLAG_EXISTING_CONNECT | If possible, reuses the existing connections to the server for new requests generated by InternetOpenUrl instead of creating a new session for each request. This flag is useful only for FTP connections, since FTP is the only protocol that typically performs multiple operations during the same session. The Win32 Internet API caches a single connection handle for each HINTERNET handle generated by InternetOpen. |
| INTERNET_FLAG-HYPERLINK | Forces a reload if there was no Expires time and no Last-Modified time returned from the server when determining whether to reload the item from the network. |
| INTERNET_FLAG_IGNORE_CERT_CN_INVALID | Disables Win32 Internet function checking of SSL/PCT-based certificates that are returned from the server against the host name given in the request. Win32 Internet functions use a simple check against certificates by comparing for matching host names and simple wildcarding rules for HTTP requests. |
| INTERNET_FLAG_IGNORE_CERT_DATE_INVALID | Disables Win32 Internet function checking of SSL/PCT-based certificates for proper validity dates for HTTP requests. |
| INTERNET_FLAG_IGNORE_REDIRECT_TO_HTTP | Disables the ability of the Win32 Internet functions to detect this special type of redirect. When this flag is used, Win32 Internet functions transparently allow redirects from HTTPS to HTTP URLs. |
| INTERNET_FLAG_IGNORE_REDIRECT_TO_HTTPS | Disables the ability of the Win32 Internet functions to detect this special type of redirect. When this flag is used, Win32 Internet functions transparently allow redirects from HTTP to HTTPS URLs. |
| INTERNET_FLAG_KEEP_CONNECTION | Uses keep-alive semantics, if available, for the connection for HTTP requests. This flag is required for Microsoft Network (MSN), NT LAN Manager (NTLM), and other types of authentication. |
| INTERNET_FLAG_MAKE_PERSISTENT | No longer supported. |
| INTERNET_FLAG_MUST_CACHE_REQUEST | Causes a temporary file to be created if the file cannot be cached. Identical to the preferred value INTERNET_FLAG_NEED_FILE. |
| INTERNET_FLAG_NEED_FILE | Causes a temporary file to be created if the file cannot be cached. |
| INTERNET_FLAG_NO_AUTH | Does not attempt authentication automatically for HTTP requests. |
| INTERNET_FLAG_NO_AUTO_REDIRECT | Does not automatically handle redirection for HTTP requests only. |
| INTERNET_FLAG_NO_CACHE_WRITE | Does not cache the data, either locally or in any gateways. |
| INTERNET_FLAG_NO_COOKIES | Does not automatically add cookie headers to requests, and does not automatically add returned cookies to the cookie database for HTTP requests. |
| INTERNET_FLAG_NO_UI | Disables the cookie dialog box. |
| INTERNET_FLAG_PASSIVE | Uses passive FTP semantics for FTP files and directories. |
| INTERNET_FLAG_RAW_DATA | Returns the data as a WIN32_FIND_DATA structure when retrieving FTP directory information. If this flag is not specified or if the call was made through a CERN proxy, InternetOpenUrl returns an HTML version of the directory. |
| INTERNET_FLAG_PRAGMA_NOCACHE | Forces the request to be resolved by the origin server, even if a cached copy exists on the proxy. |
| INTERNET_FLAG_READ_PREFETCH | This flag is currently disabled. |
| INTERNET_FLAG_RELOAD | Gets the data from the wire even if it is locally cached. |
| INTERNET_FLAG_RESYNCHRONIZE | Reloads HTTP resources if the resource has been modified since the last time it was downloaded. All FTP resources are reloaded. |
| INTERNET_FLAG_SECURE | Requests secure transactions on the wire with SSL or PCT. This flag applies to HTTP requests only. |
dwContext
Application-defined value that is passed, along with the returned handle, to any callback functions.
Return Values
A valid handle to the FTP or HTTP URL indicates that the connection is successfully established. NULL indicates that the connection fails. To get extended error information, call GetLastError. To determine why access to the service was denied, call InternetGetLastResponseInfo.
Windows CE Remarks
Windows CE supports only FTP and HTTP protocols. Only URLs beginning with FTP:, HTTP:, or secure HTTP (HTTPS:): are supported.
Windows CE supports only the following values for the dwFlags parameter:
The dwContext parameter allows for progress status callbacks to the application, but all requests are handled synchronously.
When establishing a Secure Sockets Layer (SSL) or Private Communications Technology, the following two options can be used in InternetOpenUrl to ignore invalid certificate errors:
INTERNET_FLAG_IGNORE_CERT_CN_INVALID
This ignores errors caused when the certificate host name of the server does not match the host name in the request.
INTERNET_FLAG_IGNORE_CERT_DATE_INVALID
This ignores errors caused by an expired server certificate.
Remarks
This is a general function that an application can use to retrieve data over any of the protocols that the Win32 Internet functions support. This function is particularly useful when the application does not need to access the particulars of a protocol, but only requires the data corresponding to a URL. The InternetOpenUrl function parses the URL string, establishes a connection to the server, and prepares to download the data identified by the URL. The application can then use InternetReadFile (for files) or InternetFindNextFile (for directories) to retrieve the URL data. It is not necessary to call InternetConnect before InternetOpenUrl.
Use InternetCloseHandle to close the handle returned from InternetOpenUrl. However, note that closing the handle before all the URL data has been read results in the connection being terminated.