if ($nread && $s->{opts}{86}{remote_enabled}) {
            
            my ($nout, $status) = $zlib->inflate($s->{buf});
            if (! defined $nout) {
                
                print "Error inflating: errnum: $status\n";
            
            } else {
                
                # Inflation successful
                $s->{buf} = $nout;
                $nread = length ($nout);
            }
        }
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print "Error inflating: errnum: $status\n";
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OP here. Looks like the MyTelnet->_fillbuf function is never actually called, due to some inheritance problem.

Darned if I can see why inheritance doesn't work as expected:

#!/usr/bin/perl --

my $connectObj = MyTelnet->new();
$connectObj->open(
    Host        => 'iberiamud.mooo.com',
    Port        => 5900,
);

while (1) {}        # Poor man's main loop

{ package MyTelnet;

    use base ("Net::Telnet");
    
    sub _fillbuf {
        print "This function is never called\n";
        print "Base class's ->_fillbuf function is called instead\n";
    }
}
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Regarding the call to inflate. My production code (which probably has no inheritance problems, as it generates billions of debug messages that actually appear) was producing:

Error: No output
status: data error
msg: incorrect header check
[download]

I tried ignoring everything before the first ASCII 120 character, which is where the zlib stream is supposed to start. The first couple of calls to Compress::Zlib->inflate then succeed. After that, we're back to square one, with new error messages:

Error: No output
status: data error
msg: invalid code lengths set
[download]

The zlib docs suggest this kind of error appears if the compressed stream is corrupted, but I haven't yet found anything in Net::Telnet that might be responsible.

Net::Telnet doesn't easily lend itself to subclassing, at least not in the way you want to use it. It calls the (private) subroutine _fillbuf as:

&_fillbuf($self, $s, 0);
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... which will never respect inheritance.

Before copying and rewriting Net::Telnet in a more approachable manner, you can monkey-patch Net::Telnet instead of inheriting:

require Net::Telnet;
{
no warnings 'redefine';
*Net::Telnet::_fillbuf = sub {
    ...
};
};

my $connectObj = Net::Telnet->new();
$connectObj->open(
    Host        => 'iberiamud.mooo.com',
    Port        => 5900,
);
[download]