InternetConnect

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InternetConnect

HINTERNET InternetConnect( IN HINTERNET hInternetSession, IN LPCSTR lpszServerName, IN INTERNET_PORT nServerPort, IN LPCSTR lpszUsername, IN LPCSTR lpszPassword, IN DWORD dwService, IN DWORD dwFlags, IN DWORD dwContext );

Opens an FTP, Gopher, or HTTP session for a given site.

Returns a valid handle to the FTP, Gopher, or HTTP session if the connection is successful, or NULL otherwise. To get extended error information, call

GetLastError. An application can also use InternetGetLastResponseInfo to determine why access to the service was denied.

hInternetSession

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

lpszServerName

Address of 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. Can be one of the values in the following list. These flags set only the port that will be used. The service is set by the value of dwService.

INTERNET_DEFAULT_FTP_PORT	Uses the default port for FTP servers (port 21).
INTERNET_DEFAULT_GOPHER_PORT	Uses the default port for Gopher servers (port 70).
INTERNET_DEFAULT_HTTP_PORT	Uses the default port for HTTP servers (port 80).
INTERNET_DEFAULT_HTTPS_PORT	Uses the default port for HTTPS servers (port 443).
INTERNET_DEFAULT_SOCKS_PORT	Uses the default port for SOCKS firewall servers (port 1080).
INTERNET_INVALID_PORT_NUMBER	Uses the default port for the service specified by dwService.

lpszUsername

Address of 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

Address of 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 following table describes the behavior for the four possible settings of lpszUsername and lpszPassword.

*lpszUsername*	*lpszPassword*	User name sent to FTP server	Password sent to FTP server
NULL	NULL	"anonymous"	User's e-mail name
Non-NULL string	NULL	lpszUsername	""
NULL	Non-NULL string	ERROR	ERROR
Non-NULL string	Non-NULL string	lpszUsername	lpszPassword

dwService

Type of service to access. Can be one of the following values:

INTERNET_SERVICE_FTP	FTP service.
INTERNET_SERVICE_GOPHER	Gopher service.
INTERNET_SERVICE_HTTP	HTTP service.

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

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

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 others, such as Gopher, the actual connection is not established until the application requests a specific transaction.

For maximum efficiency, applications using the Gopher and 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.


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