my $exit_requested = 0;

local $SIG{ INT  } = sub { ++$exit_requested; };
local $SIG{ TERM } = sub { ++$exit_requested; };

while ( !$exit_requested ) {
   my $client_sock = $server->accept();
   if ( !$client_sock ) {
      next if $!${ EINTR };
      die( "accept: $!\n" );
   }

   ...
}