#!/usr/bin/perl

use strict;
use warnings;

use Coro             qw( async );
use IO::Socket::INET qw( );

sub _read {
    my $rv = read($_[0], $_[1], $_[2], $_[3]||0);
    die("Read error\n") if !defined($rv);
    return if !$rv;
    die("Premature end of file\n") if $rv != $_[1];
}

sub client {
    my ($sock) = @_;

    my $host = $client->peerhost;
    print "[Accepted connection from $host]\n";

    if (defined(eval {
        for (;;) {
            _read($sock, 8, my $buf = '')
                or last;
            my $length = 0+$buf
                or next;
            _read($sock, $length, my $msg = '')
                or die("Premature end of file\n");
            print "$host said '$msg'\n";
        }
    })) {
        print "[Connection from $host terminated]\n";
    } else {
        print "[Connection from $host terminated: $@]\n";
    }
}

my $server = IO::Socket::INET->new(
    ...
) or die("Couldn't create server socket: $!\n");

async(\&client, $server->accept) while 1;