Socket programming, problem with fork

[thekira]

Hi. I've been trying to write simple server.

#!/usr/bin/perl

use strict;
use IO::Socket;
use IO::Select;

my $main = new IO::Socket::INET (LocalHost => 'localhost',
   LocalPort => 6677,
   Listen => 5,
   Proto => 'tcp',
   Reuse => 1
);
 
die unless $main;
 
$SIG{'CHLD'} = sub {
  wait;
};

while ($chld = $main->accept()) {
    my $pid = fork();

    die unless defined $pid;

    if ($pid == 0) {
       my $buf;
        print $chld "Hello world!\n";

        my $select = new IO::Select(\*STDIN, $chld);

        my @ready;

        while (@ready = $select->can_read(180)) {
           foreach (@ready) {
              my ($msg, $str);
 
              sysread($_, $msg, 2048);
 
              unless ($msg) {
                print "Quit\n";
                exit 0;
                # ---> here <---
              }
           }

        }
        exit 0;
     }
}

In this code client connects to server, sends some data and disconnects -> child process does 'exit 0'. However, parent gets SIGCHLD and exit too. My problem is that I want parent to listen at port 6677 forever...

What's wrong with this code?

Thanks in advance

 

[travs69]

Not sure what's going.. here is a piece of code I use that I know works (I wrote it 8+ years ago so no beating me up over it )

[gray]#!/usr/bin/perl[/gray]

[url=http://perldoc.perl.org/functions/use.html][black][b]use[/b][/black][/url] [green]IO::Socket[/green][red];[/red]
[black][b]use[/b][/black] [green]strict[/green][red];[/red]

[gray][i]#Set autoflush to true[/i][/gray]
[blue]$|[/blue]=[fuchsia]1[/fuchsia][red];[/red]

[gray][i]#needed to stop zombie procs[/i][/gray]
[blue]$SIG[/blue][red]{[/red][purple]CHLD[/purple][red]}[/red] = [red]'[/red][purple]IGNORE[/purple][red]'[/red][red];[/red]


[gray][i]### Socket[/i][/gray]
[url=http://perldoc.perl.org/functions/my.html][black][b]my[/b][/black][/url] [blue]$sock[/blue] = new [maroon]IO::Socket::INET[/maroon] [red]([/red][purple]LocalHost[/purple] => [red]"[/red][purple]blah[/purple][red]"[/red],
                               [purple]LocalPort[/purple] => [fuchsia]5000[/fuchsia],
                               [purple]Listen[/purple]    => [fuchsia]5[/fuchsia],
                               [purple]Proto[/purple]     => [red]'[/red][purple]tcp[/purple][red]'[/red],
                               [purple]Reuse[/purple]     => [fuchsia]1[/fuchsia],
                              [red])[/red][red];[/red]
[url=http://perldoc.perl.org/functions/die.html][black][b]die[/b][/black][/url] [red]"[/red][purple]Socket could not be created. Reason: [blue]$![/blue][purple][b]\n[/b][/purple][/purple][red]"[/red] [olive][b]unless[/b][/olive] [red]([/red][blue]$sock[/blue][red])[/red][red];[/red]

[gray][i]#Wait for new connections[/i][/gray]
[olive][b]while[/b][/olive] [red]([/red][black][b]my[/b][/black] [blue]$new_sock[/blue] = [blue]$sock[/blue]->[maroon]accept[/maroon][red]([/red][red])[/red][red])[/red] 
[red]{[/red]
	[blue]$new_sock[/blue]->[maroon]autoflush[/maroon][red]([/red][fuchsia]1[/fuchsia][red])[/red][red];[/red]
	
	[gray][i]#Fork off connection so I can listen for more connections[/i][/gray]
  	[black][b]my[/b][/black] [blue]$pid[/blue] = [url=http://perldoc.perl.org/functions/fork.html][black][b]fork[/b][/black][/url][red]([/red][red])[/red][red];[/red]
	[olive][b]if[/b][/olive] [red]([/red][blue]$pid[/blue] == [fuchsia]0[/fuchsia][red])[/red] 
	[red]{[/red]
		[url=http://perldoc.perl.org/functions/close.html][black][b]close[/b][/black][/url][red]([/red][blue]$sock[/blue][red])[/red][red];[/red]
		[black][b]my[/b][/black] [blue]@sockarray[/blue][red];[/red]	
			
		[gray][i]#Read in buffer[/i][/gray]
   		[olive][b]while[/b][/olive] [red]([/red][black][b]my[/b][/black] [blue]$buf[/blue] = <[blue]$new_sock[/blue]>[red])[/red]
    		[red]{[/red]
			[gray][i]#push info into an array[/i][/gray]
			[url=http://perldoc.perl.org/functions/push.html][black][b]push[/b][/black][/url] [blue]@sockarray[/blue], [blue]$buf[/blue][red];[/red]

			[gray][i]#if we get bye we're done[/i][/gray]
      			[olive][b]if[/b][/olive] [red]([/red][blue]$buf[/blue] =~ [red]/[/red][purple]bye[/purple][red]/[/red][red])[/red]
      			[red]{[/red]
				[black][b]close[/b][/black][red]([/red][blue]$new_sock[/blue][red])[/red][red];[/red]
      			[red]}[/red]
    		[red]}[/red]

		[gray][i]#Get rid of new lines[/i][/gray]
		[url=http://perldoc.perl.org/functions/chomp.html][black][b]chomp[/b][/black][/url] [blue]@sockarray[/blue][red];[/red]
		
		[url=http://perldoc.perl.org/functions/exit.html][black][b]exit[/b][/black][/url][red];[/red]	
  	[red]}[/red]
	[black][b]close[/b][/black][red]([/red][blue]$new_sock[/blue][red])[/red][red];[/red]
[red]}[/red]

[tt]------------------------------------------------------------
Pragmas (perl 5.8.8) used :
[ul]
[li]strict - Perl pragma to restrict unsafe constructs[/li]
[/ul]
Core (perl 5.8.8) Modules used :
[ul]
[li]IO::Socket - Object interface to socket communications[/li]
[/ul]
[/tt]

 

[thekira]

Thanks. I changed 'wait' to 'IGNORE' and it works. I thought I can't just ignore the signal... but it works

Thanks once again!