InternetConnect

This function opens an FTP or HTTP session for a specified site.

At a Glance

Syntax

HINTERNET WINAPI InternetConnect(
HINTERNET hInternet, LPCTSTR lpszServerName,
INTERNET_PORT nServerPort, LPCTSTR lpszUserName ,
LPCTSTR lpszPassword , DWORD dwService, DWORD dwFlags,
DWORD dwContext);

Parameters

hInternet

Handle to the current Internet session. The handle must have been returned by a previous call to InternetOpen.

lpszServerName

Long pointer to a null-terminated string that contains the host name of an Internet server. Alternately, the string can contain the IP number of the site in ASCII dotted-decimal format (for example, 11.0.1.45).

nServerPort

Number of the TCP/IP port on the server to connect to. It is one of the following values. These flags set only the port that will be used. The service is set by the value of dwService.

lpszUserName

Long pointer to a null-terminated string that contains the name of the user to log on. If this parameter is NULL, the function uses an appropriate default, except for HTTP; a NULL parameter in HTTP causes the server to return an error. For the FTP protocol, the default is "anonymous".

lpszPassword

Long pointer to a null-terminated string that contains the password to use to log on. If both lpszPassword and lpszUserName are NULL, the function uses the default "anonymous" password. In the case of FTP, the default password is the user's e-mail name. If lpszPassword is NULL, but lpszUserName is not NULL, the function uses a blank password. The behavior for the four possible settings of lpszUserName and lpszPassword is described in the following table.

dwService

Specifies the type of service to access. It is one of the following values:

dwFlags

Flags specific to the service used. When the value of dwService is INTERNET_SERVICE_FTP, INTERNET_FLAG_PASSIVE causes the application to use passive FTP semantics.

dwContext

Specifies the application-defined value that is used to identify the application context for the returned handle in callbacks.

Return Values

A valid handle to the FTP or HTTP session if the connection indicates success. NULL indicates failure. To get extended error information, call GetLastError. An application can also use InternetGetLastResponseInfo to determine why access to the service was denied.

Windows CE Remarks

The InternetConnect function returns a valid handle to the FTP or HTTP session if the connection is successful, or NULL otherwise.

The dwService parameter accepts INTERNET_SERVICE_FTP and INTERNET_SERVICE_HTTP as the types of service/protocol for use in the connection. However, it does not accept INTERNET_SERVICE_GOPHER, as GOPHER is not supported in Windows CE.

If DwFlags is set with INTERNET_FLAG_PASSIVE, the data transfers for the current FTP session occur in passive mode. INTERNET_FLAG_SECURE is not supported.

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, InternetConnect uses INTERNET_DEFAULT_HTTPS_PORT instead of INTERNET_INVALID_PORT_NUMBER or INTERNET_DEFAULT_HTTP_PORT.

Remarks

The InternetConnect function is required before communicating with any Internet service.

Having a connect function for all protocols, even those that do not use persistent connections, lets an application communicate common information about several requests by using a single function call. In addition, this allows for future versions of Internet protocols that do not require a connection to be established for every client request.

For FTP sites, InternetConnect actually establishes a connection with the server.

For maximum efficiency, applications using the HTTP protocols should try to minimize calls to InternetConnect and avoid calling this function for every transaction requested by the user. One way to accomplish this is to keep a small cache of handles returned from InternetConnect; when the user makes a request to a previously accessed server, that session handle is still available.

An application that needs to display multiline text information sent by an FTP server can use InternetGetLastResponseInfo to retrieve the text.

For FTP connections, if lpszUsername is NULL, InternetConnect sends the string "anonymous" as the user name. If lpszPassword is NULL, InternetConnect attempts to use the user's e-mail name as the password.

To close the handle returned from InternetConnect, the application should call InternetCloseHandle. This function disconnects the client from the server and frees all resources associated with the connection.