Laravel – A JOIN With Additional Conditions Using Query Builder or Eloquent

I'm trying to add a condition using a JOIN query with Laravel Query Builder.

<?php

$results = DB::select('
       SELECT DISTINCT 
          *
          FROM 
             rooms 
                LEFT JOIN bookings  
                   ON rooms.id = bookings.room_type_id
                  AND (  bookings.arrival between ? and ?
                      OR bookings.departure between ? and ? )
          WHERE
                bookings.room_type_id IS NULL
          LIMIT 20',
    array('2012-05-01', '2012-05-10', '2012-05-01', '2012-05-10')
);

I know I can use Raw Expressions but then there will be SQL injection points. I've tried the following with Query Builder but the generated query (and obviously, query results) aren't what I intended:

$results = DB::table('rooms')
    ->distinct()
    ->leftJoin('bookings', function ($join) {
        $join->on('rooms.id', '=', 'bookings.room_type_id');
    })
    ->whereBetween('arrival', array('2012-05-01', '2012-05-10'))
    ->whereBetween('departure', array('2012-05-01', '2012-05-10'))
    ->where('bookings.room_type_id', '=', null)
    ->get();

This is the generated query by Laravel:

select distinct * from `room_type_info`
    left join `bookings` 
on `room_type_info`.`id` = `bookings`.`room_type_id` 
where `arrival` between ? and ? 
    and `departure` between ? and ? 
    and `bookings`.`room_type_id` is null

As you can see, the query output doesn't have the structure (especially under JOIN scope). Is it possible to add additional conditions under the JOIN?

How can I build the same query using Laravel's Query Builder (if possible) Is it better to use Eloquent, or should stay with DB::select?