Win98 socket woes

Dinosaur has asked for the wisdom of the Perl Monks concerning the following question:

Sort of in the same vein as Bi directional Socket question:

I can't get a pair of processes to communicate by socket, under Win98 with ActiveState perl 5.6.1.

I've read the Perl Cookbook ch. 17 advice, and also the relevant sections of Mastering perl/Tk (since that's what I'm trying to do, move some heavy lifting to a separate process so as not to slow down GUI response). What I'm doing, I think, is right in line with their recommendations. I've tried various permutations of parameters, with no success.

Code is below. When I run it, I get the following messages:

child started IO::Socket::INET=GLOB(0x204aeb8)
child read failed: Invalid argument at E:\Perls\sock_hop.pl line 63.
parent started IO::Socket::INET=GLOB(0x176541c)
parent sending
parent sending
parent sending
parent write failed: Invalid argument
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... of which the failed read in the child seems to be the smoking gun. "Invalid argument" presumably refers to the file handle -- but what's its problem?

If anyone here can take a minute to look at the attached code snippet, I'd be grateful.

--Dinosaur

use strict;
use warnings;

use IO::Socket;

sub process;
sub parent;
sub child;

use vars qw[$PARENT $CHILD];

process;
exit;

sub process {

   $PARENT = IO::Socket::INET->new(
                 Type => SOCK_STREAM,
                 Proto => 'tcp',
                 LocalHost => 'localhost',
                 LocalPort => 9969,
                 Listen => 5,
                 );
   die "parent socket failed: $!\n" unless defined $PARENT;
    
   $CHILD = IO::Socket::INET->new(
                 Type => SOCK_STREAM,
                 Proto => 'tcp',
                 PeerAddr => 'localhost',
                 PeerPort => 9969,
                 );
   die "child socket failed: $!\n" unless defined $CHILD;
    
   if (my $pid = fork()) {
      close $PARENT;
      parent;
   } else {
      die "fork failed: $!\n" unless defined $pid;
      close $CHILD;
      child;
   }

}

sub parent {

   print STDERR "parent started $CHILD\n";

   while (1) {
      print STDERR "parent sending\n";
      print $CHILD "Hello from parent\n" or die "parent write failed: 
+$!\n";
      sleep 2;
   }
    
}

sub child {

   print STDERR "child started $PARENT\n";

   while (1) {
      my $line = readline ($PARENT);
      die "child read failed: $!" unless defined $line;
      print STDERR $line;
   }

}
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Comment on Win98 socket woes Select or Download Code

Replies are listed 'Best First'.
Re: Win98 socket woes by perlplexer (Hermit) on Apr 08, 2002 at 14:00 UTC
You can't read/write from/to the socket that you are listening on ($PARENT in your case). You need to call accept() first. See this section of perlipc for details. --perlplexer	[reply]
Re: Re: Win98 socket woes by Dinosaur (Beadle) on Apr 08, 2002 at 18:50 UTC
But I'm not listening on $PARENT, ... AAAARRRGGGHHHH!!! It's BACKWARDS! I knew I'd get confused if I didn't think up better names for the two filehandles. I'll have to wait until I get home to try it, but that should do the trick. Thanks, 'plexer. --Dinosaur	[reply]