I have, at last, gotten it all working. It took some tweaking and wasn't all that easy to figure out. My environment is that I do two types of interactions on my IO::Socket::INET. One is a simple command->{one line} response. The other is a multi-line response, but the same basic structure: command->{one line} response->{multiline data ended by a line with just '." on it. Here's the working code: 
$server = IO::Socket::INET->new(...) ;
abort("Can't connect to news server: $!") unless $server ;
$socket = IO::Select->new($server) ;

my $linebuffer;

# send a command to the server, 1,2, or 3 are success responses.
##  This really can't hang, so we can just go for it [no timeout]
sub command
{   my $cmd = "$_[0]\r\n" ;
    print $server $cmd ;
    $linebuffer = "" ;
    my $resp = getline() ;
    return undef if $resp !~ /^[123]/ ;
    return $resp ;
}
 
# return a multi-line response from the server
##  We return it a line at a time with timeouts if the server barfs
sub multi
{   my $cmd = $_[0] ;   
    if ($cmd) 
    {   return (command($cmd)) ; }
    return getline() ;
}

sub getline
{   my @readstatus ;
    if  ($linebuffer =~ s/(^.*?\n)// )
    {   return $1 ; }
    while(@readstatus = $socket->can_read(2)
        and sysread $server, $linebuffer, 4096, length $linebuffer)
    {   next unless $linebuffer =~ s/(^.*?\n)// ;
        return $1 ;
    }
    # if you get here, something went wrong!
    warn(@readstatus ? "socket closed\n" : "timeout\n") ;
    return undef ;
}

[download]
The main program that uses this looks like: 
die "command error\n" unless multi("command") ;
while (1)
{   my $line = multi() ;
    last if $line =~ /^./ ;
    {process the line}
}

[download]
One other trickiness is that I couldn't get the timeout to work cleanly -- if something went wrong I had a hard time figuring out whether it was recoverable or not. So, I embedded the entire main program in a child fork and the child fork exits with a non-zero status if timeout happens or the connection is lost or if anything else happens. The parent then re-forks and starts the child over again from the beginning. If the child returns with a 0 status the parent just exits.

In reply to Re^10: IO::Socket tutorial by BernieC
in thread IO::Socket tutorial by BernieC

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