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How do I detect whether of not an Internet connection exists?

Posted on 1997-04-06
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Last Modified: 2010-04-06
My problem is that I need to test whether or not a connection to the internet exists in windows95.  The obvious solution is to test your own IP address and compare it to 127.0.0.1 .  If the comparison is true, your offline.  Any other IP address means your online.

The problem is that with windows95, any call to winsock triggers the dialer.  I DO NOT want to trigger the dialer if there is no connection to the internet.

So, I guess my question is:

   How do I make a call to Winsock without triggering the dialer?

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Question by:sleach
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by:sleach
ID: 1335217
Edited text of question
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by:sleach
ID: 1335218
Adjusted points to 204
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sperling earned 200 total points
ID: 1335219
Might work using the RasEnumConnections API call...

If you need help using this function, let me know.

Regards,

Erik.
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by:sleach
ID: 1335220
sperling, I am unfamiliar with RAS.  Can you point me to a code example?  

Also, will RasEnumConnections show only dial up networking connections, or will it also show connections from other dialers(such as AOL's 32 bit dialer)?

I am currently using FindWindow to detect the Win95 Dialer, but this only works with the Win95 Dialer.  I need a method thats Dialer independant.

Can RAS be used to disable the AutoDial feature?
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Expert Comment

by:sperling
ID: 1335221
>sperling, I am unfamiliar with RAS. Can you point me to a code
>example?

So am I ;)

I haven't got any modems installed, and I don't run 95... Therefore I can just suggest that you make a small test program displaying RasEnumConnections output in an ButtonClick event, and then tries to figure out how it works by noting what output you get while offline and online using different dialers.

Sorry I can't be of more help.

Regards,

Erik.
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by:sleach
ID: 1335222
It took me awhile, but I finally figured it out.

For the purpose of sharing the solution, Here is the function that works for me.

USES ras;

function RasConnected:  boolean;
var
    rasconnbuf:  TRasConn;
    cb, ret, numConn:  integer;
    connected:  boolean;
begin

    //Required to provide buffer size
    rasconnbuf.dwSize := sizeof(rasconnbuf);
    cb := sizeof(TRasConn);

    //Retrieve info about first active connection (I only have one - change this if you have more)
    ret := RasEnumConnections(@rasconnbuf, cb, numConn);

    if ((numConn = 0) or (ret <> 0)) then connected := false
    else Connected := true;
result := connected;
end;

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