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RE: Computer connected to the internet?
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From:
Gary Hawkins
Date:
January 24, 2002 03:40
Subject:
RE: Computer connected to the internet?
Message ID:
LOBBIJFNBAGIOILLFAIBOEJBNFAA.ghawk@eskimo.com
> >How can I check whether the system is connected?
> >
> >Want to pause the script if connection is lost.
>
<snip>
>
> Instead of trying to check whether "there is an Internet connection," just
> see whether you can do whatever it is your program is using the Internet
> for.
>
<snip>
>
> Peter Scott
> peter@psdt.com
> http://www.perldebugged.com
>
I like that suggestion. So, how can I determine it based on the success of
this second line?:
&CheckOnlineState;
$request = HTTP::Request->new(HEAD => "$URL");
In the meantime, I came up with the following Win32::API read of a dll
function, which works. Supposing that the $request success test above winds up
in a catch 22 without a way to recover and retry, I would like to find some
sort of associated method (without ping) to check online state if on Linux.
Here's the one for Windows:
if ($^O eq "MSWin32") { use Win32::API; } # top of script
# The 'if' is because, for some ungodly reason my Linux-based
# ISP doesn't have Win32::API installed, imagine that.
sub CheckOnlineState { # elsewhere
return if $^O ne "MSWin32";
$IsNetworkAlive = Win32::API->new(
"SENSAPI.DLL", "IsNetworkAlive", [P], "L");
$return_code = "\0" x 4; # reserve some memory for it, why?
$IsNetworkAlive->Call( $return_code );
# or warn Win32::FormatMessage(Win32::GetLastError());
$return_code = unpack('L',$return_code); # hash otherwise?
#print "\nReturn code: $return_code\n";
if ($return_code == 0) {
print "\n\n\tConnection lost!
\tRestore and then
press any key to continue...\n\n";
`pause`;
}
# From C?: Declare Function IsNetworkAlive \
# Lib "SENSAPI.DLL" \
# (ByRef lpdwFlags As Long) As Long
# lpdw apparently = long pointer double word, so, [P].
# ... IsNetworkAlive As Long, so, "L", right?
}
That allows the script to pick up where it left off when my 2-hr-limit DSL
connection times out and I reconnect it via the any_key.
One small problem with the routine is that I see it return 2 for my particular
connection type if connected but there is supposed to be some associated
descriptive text along with that, differentiating between LAN or WAN or
something, and I don't know which is which for 1 or 2 or how to get that text.
Oh well, zero works. Thanks to those who responded, all comments were
appreciated and helpful.
That's the furthest I've gotten with Win32::API. Now it's tempting to go
bonkers looking up functions in dll's and exe's via notepad or QuickView and
run them from Perl to amuse myself. Or maybe it has a greater use, maybe girls
would just about faint when they hear this pickup line: "I access Windows
API's from Perl all the time, yeah I have complete control of Windows." :b
....have to give that a try at Starbuck's first thing in the morning. Hey I'm
in Seattle and the traffic has driven us all mad so gimme a break. :/
Gary
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