sub readn   #returns scalar with <= $bytes requested
{
    my ($socket, $bytes ) = @_;
    my $offset = 0;
   
    my $buf = "";
    my $nread = -1;
   
    while ($offset < $bytes and $nread) # $nread==0 means EOF
    { 
       my $nleft = $bytes-$offset;     
       $nread = sysread($socket, $buf, $nleft, $offset);
       $offset += $nread;    
    }
   
    return $buf;
}