my $buf = '';
my $header;
for (;;) {
   my $rv = sysread($sock, $buf, BLK_SIZE, length($buf));
   die("Can't read: $!\n") if !defined($rv);
   die("Can't read: Premature EOF\n") if !$rv;
   
   if ($buf =~ s/^(.*\r\n\r\n)//s) {
      $header = $1;
      last;
   }
}